Is my 4 month old teething, or growing?

My 4 month old son is usually so happy, but lately he has started whining a lot. He has been an absolute drool machine for the past month, and puts EVERYTHING in his mouth. When I rub his gums, it makes him happy sometimes, and then other times he just chews on my finger, but I don't feel any bumps yet. He will occasionally pull on his ears, and just in the past few days has been sleeping A LOT (not that I am complaining). One night he went 10 hours straight. I finally woke him up because that is unusual for him. He will usually go for 4-6 hours at night between feedings. I'm not sure if it's a growth spurt, or if its the continued start of teething. Any ideas?