☆.A.
Could be growing, could be teething.
Could be he "needs" and extra nap here and there sprinkled in with his O.-a-day nap. My son did that. Like 3 days of O. nap then he was sleepier and added O. sometimes.
The only times he took an unexpected late, looooooong nap--look out, he'd usually wake up with a raging fever.
So, I hope it's just growing or teething for you.
Good luck!