Right, have read the first 200 or so posts?
People who stop and stare are partially responsible for the fact that we still don?t have equality in this country. However, so are people like the op, and here?s why:
The instant you make reference to how wonderful it is that someone hasn?t mentioned a disability you make that disabled person unequal. You wouldn?t mention the fact that you were proud of not mentioning that someone was black, or Asian, or that a woman had been given a job over a man, or that a friend was gay, and yes, these comparisons are absolutely all relevant, because these are all situations where, in the past, black/Asian/women/homosexuals have been considered unequal to their counterparts and thus those differences would have been mentioned. It is only through education and campaigning and intolerance of prejudice that we have got to a point where being black or Asian or a woman or gay is no longer seen as a point of relevant difference. Obviously to some it is, but only in the negative - racism still exists, but we don?t praise people for not being racist iyswim because we just accept that black/Asian/white is equal and any other opinion is wrong.
In many instances disability has not yet reached that point. Campaigning for equality of disabled people is ongoing and much progress has been made. The disability discrimination act only came in in 1997 for instance, when I was growing up inclusion of children into a mainstream environment was seen as novel rather than the norm, yet now it is illegal to discriminate against the disabled and children are routinely educated in mainstream schools just to name two examples. But there is still a long way to go, and that is partly down to attitudes, but also partly down to the fact that because disability is so diverse, ultimate inclusion is not as straightforward as it was in examples of racism for instance, because adaptations to make everywhere inclusive are often numerous to accommodate all disabilities.
And because much disability is physically obvious, differences are noticeable and often observed either loudly by staring/commenting, or more discretely such as in the case of the op. But it?s a fact that people still notice, and still feel it?s ok to notice difference, even if it apparently doesn?t bother them that the difference exists.
In an ideal world, people with disabilities will be seen in the same way as people who are black/Asian/who are women and difference will be something which isn?t relevant and thus not raised as a point of issue.
But while people like the op express pride that her daughter sees someone with a disability as an equal rather than someone to be stared at, this equality is still stalling.
Not noticing is of course a positive. But noticing that someone didn?t notice isn?t ? because it immediately brings back the emphasis on the fact the difference exists ? the difference which the daughter didn?t see fit to notice, in the same way she wouldn?t notice if the girl had been black or Asian. Drawing attention to not noticing turns a positive into a negative.
It was obviously relevant to the op that this girl had a disability, relevant enough to ask why.
Perhaps the op was in fact more embarrassed that she herself had noticed the difference rather than proud of the fact her daughter had not.
Fwiw I am considered to have a disability ? I have been blind since birth. And yes of course people notice ? I tend to find the Labrador is a bit of a giveaway. ;) sDo people stare? Probably. But I am blessed with the inability to see them. 
Are there people who are negative about the visually impaired ? almost certainly, although on the whole I have encountered very little actual prejudice. However if someone praised any of my sighted friends for not making my blindness an issue that would be far more patronising and hurtful than any blatantly negative comments. Because it implies that it should be an issue, and that it not being an issue is praiseworthy in a society where to many it would be. And why should it be an issue ? it shouldn?t,.
So op ? to be bursting with pride that your daughter is not prejudiced against the disabled ? she is just a normal girl ? the fact that man others do not react this way does not make her behaviour not what should be considered the norm iyswim.