I think there are two separate issues here:
a)The obvious pride that any parent is going to feel in a bright child who learns things easily and is a pleasure to be with
this is what I think the OP is mainly about, and nothing at all to be ashamed of. Being proud of our children is one of the most important things we do.
b) The tendency a few parents have to believe that if their 3yo is bright, this has got to carry on in later years, and that if this child does not do well in life/get into Oxbridge, then something has gone wrong, someone- either the parent or the child or the school- has let him or her down.
this tendency can obviously lead to all sorts of negative results: too much pressure on a child, unrealistic expectations on the school, unnecessary disappointment if a bright 3yo turns out to be a perfectly average 9yo, dismay as the late developers in the class start catching up etc
It's because we've had some such posters in the past, that some MNers are very keen to point out that early brightness is not a fail-proof sign of later giftedness. SO far, they are right. It isn't.
But- as long as you are happy to enjoy it in the present and not tie yourself down to any very definite ideas about the future, there's no reason why noticing your child's giftedness is a problem. Like good looks or a kindly manner, it's there for you to enjoy!
(The only thing I would guard against is letting your dd know if you think she is cleverer than you. I know a child who is quite bright and whose Mum consistently adopts the humble role- as he grows up, it's getting a bit obvious that he expects to be the cleverest person in the room and other adults tend not to take kindly to this).