I have heard this asked several times, and yes, it was usually directed at the only non-white people in the exit rows. If they ask one, they should ask all. I've also seen age questioned (whether or not they were the minimum 15 years of age). Never once have I heard an FA specifically ask if they people could lift the 33lb door though... That worries me much more than anything else. Many times I've seen people in the exit row who can't even manage to lift their own carry on, let alone the door.

For the first time yesterday I did see someone move out of an exit row on a UX flight. After being asked the question about sitting in an exit row, she got up and voluntarily moved to another row and another passenger replaced her. I've NEVER seen that happen. Couldn't hear what the reason was though.