Me it's, thanks for thinking about it and coming back.
From my perspective, when I am going about my day to day life, I find being asked - are you ok? What's wrong with your leg? There's a loft over there you know! - actually quite upsetting.
I see myself as a normal happy person, getting on with my day to day life and this is a jolt back to reality that all they see is a lurching cripple.
If I want help I will ask for it.
I hope I can distinguish between the kind and the nosy twats and not get offended unnecessarily, but what you also have to remember is that a lot of us who are disabled have spent entire child hoods being bullied about this - when an adult asks what's wrong with my leg, my first primal response is to want to hit them, as that is how I had to defend myself as a child.
It should be relatively easy to spot the 'new limper' who would welcome your concern and offer of a plaster and someone who is a well established limper - I.e. Getting on with their day, looking cheerful, not asking for any help.
And btw when I was pregnant and no fucker offered me a seat, I just said 'I need that seat!' ( as was about to faint/throw up) and man leapt off seat as if on fire. I think on public transport people are in their bubble so won't necessarily notice you and you have to speak up.