After my bone graft my gums feels like there's an empty hole. Is this normal?

Hello!
A 'hole' feeling is normal since you're used to there being an implant/tooth there. The graft needs time to integrate with your bone and as it does it will fill in. It's possible that even after that, you may still feel like there's a hole remaining or a space or dent, because there is no implant/tooth. I think you should be fine, but ultimately, if it continues to concern you, don't hesitate to contact your dentist and go in to have him give it a once over.
Good luck!

Hi:Most likely this is normal.  However, X-ray and photo is necessary for more accurate advice.  If you are concerned, please contact your dentist.Best,Dr. Maddahi