Jonathan has been waking up mid-nap, about 30 minutes in. Yesterday this happened twice in one nap, and today it has happened during both naps. He goes right back to sleep if I go in, lay him back down, and lie down with him for 2 or 3 minutes. It is a little strange. I don't mind helping him back to sleep, but it seems like he's not sleeping well if he's waking up in the middle...ideas?