H.B.
Hi there. Baby's seem to go through phases. My daughter is 15 months now. and there was a point last year. where she went from a nice 7 am.. to 6 then 5.. then back..Now she's typically 630 or 7. Another reason could be sunlight coming into the room and waking him up. now that it is getting lighter earlier.. Maybe try keeping him up a bit later. although it seems no matter what time my little one goes to bed... she gets up at the same time.
I would give it a week or so see if she starts to shift back