sign language and the word MORE

So, just a little bit ago, I was taking a drink of some root beer and Mac loves to sip on root beer. He had a little sip and looked at the bottle sitting on the desk and tried reaching for it. I asked him if he wanted more, looked down at him, and he was doing the sign for more, which for those of you who don't know, is bringing both hands together by touching the four fingers together--like one would do to cross their fingers togeter...ok so it's really hard to explain, but he did it none-the-less! I haven't worked with him on doing that since the summer time at least!