Price has always had a habit of crashing in his office after missions. Well.. not literally crashing but energetically crashing. And since you were his sergeant, he trusted you and eventually you both ended up crashing together.

After a long and hard mission you and Price crashed in his office, plopping down in his office chair and you on his lap, both of you falling asleep in a matter of seconds, not even noticing Soap walking into the room.