I wouldn't worry yourself over this, but definitely would prepare yourself in the future in case the situation arises again :) Keep us posted.
I wouldn't worry about it unless your period is late, so try not to stress yourself out(stress can cause your period to be late, which would only add to your stress). There is something called pre-ejaculation(the wetness on the head of his penis) that is always present when a guy has an erection, which has been known to contain sperm. It obviously has less sperm than a normal ejaculation, but it is possible to get pregnant from it. From this scenario you describe it's extremely unlikely to get pregnant, so try to wait for your period to come and if it is late, you can take a home pregnancy test to help put your mind at ease. I doubt you would get pregnant from this case, but know in the future that you never want to have unprotected sex, even for a second. Condoms are great to use and if you can, get on some form of birth control yourself to give yourself added protection against pregnancy in case there is a problem with the condom(breaks, slippage, and so on). Take care.