1 or 2 weeks ago, my boyfriend and i were in my bed fooling around. he got on top of me and took his penis out, my underwear was halfway off. he put the tip of his penis right outside of my vaginal hole (he was not inside, but if i wanted to, he could just push and he;d be right in) i;ve noticed that he does pre-ejactulate when he is aroused, so WHAT IF he did pre-ejactulate and it traveled up my vagina. is that possible? what are the chances of me being pregnant? should i be concerned?