Roommates boyfriend harrassing me

Im a 20 yo female college student. I have a roommate, a girl in my class that ive known since middleschool. I never wear clothes around the house, sometimes a tshirt and thong, being that its just us, Sometimes i wont even wear underwear. Once again, she dressed like this too, because were comfortable like that. Recently she started bringing this guy to our apartment every once in a while, mabye 3 days a week. The problem is, i sometimes sleep late, and they would come back to the apartment early in the morning at like, 1AM. Being that i get up to get late night snacks, I would see this guy often times while im eating something quick. The thing is, i sleep nude, so when i get up to get the late night snacks, i just walk to the kitchen like that. The dude actually started coming into the kitchen at the same time as i did, and eventually started harrassing me, Telling me how attractive i am, at first i thought this was normal, and that he was being friendly. Then he asked for sex. This shocked me, and i simply jusy got up and went back to bed. Im debating on weather i should tell my room mate or not. The Question is; Is it normal for a guy to do this?