Anyone else's 4 month old sleeping more than usual?

My 4 month old son always had a few naps through the day but they lasted only a half hour to 45 minutes at a time. The last few days he's having marathon naps--3 hours at a time! I am assuming it's teething / growth spurt related? He's definitely showing signs of teething. Just wondering if any other mama's are noticing sleep changes? He's pretty much the same at night as he's always been.