We were at a restaurant last weekend and he signed more cheese without us prompting him, which made me very happy. Tonight he signed more eat on his own, so I think he might have the more concept down, but I don't really know.
Edited to add... Does anyone else have more trouble with their husband learning the signs then their child? My husband is one of the smartest people I know and he just can't get the difference between some of the signs. We watch Baby Signing Time and he signs along and loves it, but he just isn't very accurate.