No membrane used for graft on tooth #8. Is this normal practice?

I had tooth #8 extracted two weeks ago due to accident, and a graft was placed for future implant. No membrane was used leaving the synthetic graft material exposed. A small chunk of graft material came out yesterday in one clump and I am wondering if this normal? Is the graft supposed to be flush with the bottom of the gum or is this slight crater looking appearance ok? Thank you.