I had oral sex with a man of unknown status. I had a small cut on my hand (not bleeding) Is there any chance of HIV infection if semen got on the cut?

Little or no risk. There has never been a known (or even suspected) case of HIV from contact of semen with cuts on the hands or elsewhere. The oral sex itself probably was higher risk, and even that is considered zero risk for all practical purposes. Don't worry about it. Or ask your partner about his HIV status (which you should have done before contact). If negative, of course no risk. Good luck.