Blood clot after bone graft?

I had bone graft on the upper front part of my mouth (laterals) yesterday. My dentist shaved the top part of my dentures and put it back in right after surgery. Had some proteint shake, brushed lower teeth and drank lots of water. Now before going to bed, I took off my dentures and saw a ball of blood clot hanging from my gums where the surgery was. Is it normal? My dentist will be off tom. And now I'm panicking if I did something wrong.