Help! my DS wont tell me he needs to go potty, but used to.

My DS just turned 3 and was pretty trained for about 3 months before his bday. He would tell me, go potty and almost always went, except poop, but thats for another day. So for like the last 6 weeks or so, if you can drag him in there he will usually go, but he will not tell us he needs to go.  Daycare says he tells them and he is remaining dry most of the day.  I can't figure out why he wont't do this at home and what to do about it. Help.