Bruising After Seeing a Dentist?

I went in for 2 fillings on my bottom right side. When I got home, I had a purple bruise on the upper right side of my cheek. Is this normal? I am still frozen so I cant tell if there's any tenderness anywhere. I have had fillings before, even all 4 wisdom teeth extracted with no swelling or bruising, so I was just a little shocked to see a bruise, and one thats not even in the area where I had work done.