Looking back at Uniden's reply, I guess the more simple answer is: if a card is flipped or exposed through dealer error, the card is replaced (i. e.catches some air and turns over)...if the card is flipped by the player, or flipped because it hit the players hand, it will remain in play.
This does not correspond with the way Uniden's room handles the situation but, it seems the more practical solution, in my opinion. Telling a player that his Ace must be replaced because it hit his hand and was exposed might be a difficult rule to enforce. In fact, I'm starting to rethink replacing any "proper card" that is exposed.
Always an interesting topic. It reminds me of the card off the table that "must" be replaced, even when it is never really exposed, and lands face down on the floor.
Don't know if I'm offering any solid answers to Guillaume's original question but I guess the best solution is to be sure your house rules clearly state the way you are going to handle this situation.