Signing "more"

I started doing the signs for "more" and "all done" when Tyson was about six months old.  This week he suddenly started doing the signs!  In the videos below he does both signs on his own (I am not demonstrating the signs for him when I say the words).  I am excited about his ability to start communicating and am planning to add a few more signs, including "milk," "eat," and "read."