General

As much as I find bigger ladies attractive, I try not to stare, just in case it makes them feel uncomfortable. I know they are there, and I appreciate that. If I knew that they wanted my attention, it would be more than likely that I'd say hello.
I don't stare and check them out for too long, just in case they are offended by it. Who knows in todays society.

Maybe they're fatophobic FAs--that is, they're attracted to you but don't want to be because of social conventions or their own cowardice or whatever.

So they turn away to suppress their attraction.