ED QUESTION!

My boyfriend suffers from errectile dysfunction sometimes and most of the time we use a condom. Tonight we were having unprotected sex and he went soft, no biggie. So I went to the bathroom after to pee and clean up and I think he may have cum inside of me a little bit without realizing it, because he didn't orgasm. Is this possible? I'm on Nuvaring for birth control, so should I take Plan B or do you ladies think I'm safe?