confused

Kohen usually takes VERY short naps throughout the day.  He will eat, play, nap....eat, play, nap.  He naps range anywhere from 5-20 minutes.  Today has been different.  He slept all night long, woke up at 7:30ish this morning and we did our usual routine.  Around 10:15 a.m. I gave him a little cereal and 4oz. of formula.  He went to sleep around 10:30a.m.  He didn't wake up until NOON.  He slept over 1.5 hours.  I thought wow!  I can't believe he slept that long.  When he woke up we played, I gave him a bath, he ate about 5oz. of formula.  I was holding him upright walking around picking up when I noticed he had fallen asleep AGAIN (this time on my shoulder) .  He was completely out like he was this morning (this morning I was bouncing him on my knee and I noticed his head droop over and he was conked  out).  I usually have to walk with him and snuggle him to get him to sleep.  I'm freaking out a little.  I keep going to check on him to make sure he's breathing!  Did any of your kids go though this change of sleep pattern???  Who knows, it may only be for this one day.  I know I should be thankful, but I can't help but be worried!  Seriously, let me know what you think!!!!