marvin347, thanks for bringing this up, has been bothering me as well for a while !
You don't say it, but I presume you're talking about a climbing / descending turn.
I'm still in doubt about the "staircase explanation" because of these two practical aspects:
1. Airplanes don't turn "on the spot", they generally make very wide turns. The wing span is tiny in comparison with the diameter of the turn. Wouldn't other factors like dirt on the leading edges, small differences in wing assembly, etc. have a even greater effect ?
2. The climb speed of GA airplanes is microscopic compared to their forward speed. The increased AoA due to the upwards movement of the aircraft must be minimal. Otherwise as above.
I haven't been able to stall myself such that a wing drops. My flight instructor did demonstrate this, but in 1 out of 3 cases the "wrong" wing dropped. I've also read that on C152s, the "wrong" wing may just as well drop.