I had an experience with a masseuse recently were she seemed to rub herself against my genitals. She had underwear on, whereas I was naked

I was a bit alarmed. She was on top of me but lying horizontally rather than straddling me, so I couldn't really make out what the exact contact was. Saying that, that particular contacted lasted no more than 20 secs

I didn't want to be a jerk and ask her to stop, nor did I want to piss her off after by asking what sort of contact was being made

Anyway, I'm a tad worried about the usual concerns involving skin to skin contact

Advice, thoughts please. No smart arse replies please