Did I traumatize my 6 month old by letting him fall off the bed?

I never meant for it to happen. The day it did happen, he had just learned to roll from belly to back and even then he would roll onto his back and then just stay there he wouldn't roll over again. Well the day it happened I laid him on the bed and put him the very middle, ran to the bathroom really quick and I heard a thump and then a scream. I was like OMG he fell off. I ran back in there and he was of course laying on the floor. Thankfully we had just taken the risers and the frame off and put our mattresses on the floor otherwise he would have fell about 4 ft, he only fell 18 inches. Anyway ever since the fall he hasn't even tried to roll from belly to back, but will still roll from back to belly. Do you think I traumatized him?