Late naps now! Normal???

My one and a half year old has been napping late lately! He's sleeping 12 hours at night now. And his naptime is now 2-2:30 instead of 12-12:30. He will play in his crib for literally 1-2 hours before falling asleep!! He's been stuffy lately (cold, allergies?). He has molars coming in (Orajel has been a God send). Is he on a growth spurt too or something? Does he know he's about to have a sibling this week and he's changing his ways?? What do you think could be going on?