Ball python drool? Ball python yawning?

My 2 year old Pastel Ball Python has only drooled once, I was holding him and my mom said "what the hell?" she starting laughing cuz she though he spit on me or something, I thought he might be sick but he hasn't done it since… Yawning too, he will do it on occasion but doest show any signs of there being something wrong… Is it normal for them to do these sorts of things, I have to snakes and 4 years in all and have never seen anything before from my first snake. (reptile/exotic vet I know says he looks good, said the colour of him is very nice ford a male and said this is a sign of good health, as long as he has good temperate and isn't stressed)