i have a friend that found out that she had HPV back in 2002. she also found out that she was pregnant at this time. i was worried like you are when she first told me but then i started reading up on HPV and found out there are many different types. my friends cleard on its on. hers was sexually transmitted. just read up on it to ease your mind. i don't think you have anything to worry about.
You could, but it is not likely after an event like this. If your friend satisfied herself using your genitals, then there is a risk. I also assumed you have more than one towel in your household.
Bottom line: I think you are worrying too much.