Too hot

Shosei has been sleeping so much these days.  Instead of having 20 to 30 minute naps, he is having 1 and a half hour naps!  Is this a growth spurt sign?  Or does he just like to sleep, like his mom does?

I caught him fallen asleep with his burp towel in his mouth.  He was sucking it so much, I could hear the saliva go through his mouth.  After he fell asleep, I had to take a picture.