Can stitches be left inside the mouth without issues? (Photo)

I had a bone graft in my mouth on teeth 7 and 10 3 weeks ago. 2 days ago I had all of my stitches removed except one stitch left in the roof of my mouth. There's no knot to cut or visible other side of the stitch. I tried to see if I could gently pull it out and it hurt badly once i tried and felt like it was pulling on something deep into my gums. It's really scaring me bc I'm thinking about all these crazy possible issues. What are the realistic issues with a stitch being left in my mouth.