Talking in his sleep?

[armywife]

My 4 month old is supposed to be taking a nap right now, but I keep hearing him talking. At first I thought that he just hadn't gone to sleep yet but I went in to check on him, and he was quiet, eyes closed, apparently asleep. I left the room again and I could hear him talking again. I went in to check on him again, and again he looked sound asleep. 4 months old is a little young to be pretending to sleep every time I come in the room. I think I want to just sit in there and watch him for a bit, but it's a little weird don't you think? Is he talking in his sleep? or is he just drifting in and out of sleep? I know that he sneezes in his sleep regularly, but talking isn't quite the same at sneezing.