Disappearing signs

All of a sudden the few baby signs that Eli had left have disappeared. The last holdouts, which have vanished in the past couple of days, were "water" and "more". He has a period of maybe a day where he will use the word and the sign interchangeably. Then the sign is gone. This is good, in a way, because I can not always see when he is signing. However, I do not always know what he is saying, so in a way it is more frustrating.