12 week old sleep

My son has been a great sleeper almost from day one. He sleeps anywhere from 6-8hrs at night and recently has been sleeping 9.5hrs. The past two nights he’s been waking up at about 3am, (he sleeps in my room) so I put him back to sleep and wakes up every hour after that.

Any suggestions on what I can try or why this might be happening?

FTM and LO is EBF

Thank you