the pill... the Plan B pill

A
WARNING: this includes graphic descriptions of sex!
So this morning, my boyfriend and I had protected sex. I have been on oral birth control for a few months and he uses a condom each time. This morning, before putting on a condom and having penetrative sex, he had rubbed the tip of his penis across my clit and vaginal opening. I was worried afterwards and picked up the Plan B pill, and took it about one hour after sex.
My question is, was there any reason for me to worry? Can you get pregnant from having contact with a penis on your vaginal opening?