Why cant I stop thinking about it? Does it mean anything? How should I give his jacket back?

I have a co-worker and we are together in university (dual). He is 24 and I am 19. I see him everyday and he is pretty, but I never thought more about it. Only encounters were me forgetting my stuff in the uni kitchen and he brought it to me or boring group work.
He is a gym guy and like 175cm/5'9 and | complimented his hair because he recently changed it.

Yesterday there was a party on campus with like 14 other classmates, me and him and hundreds of people we dont or barely know.
I was cold and he offered me his jacket and when he talked to me or wanted to move, he touched me on arm or shoulders. With one of my female uni-friends he didnt do this and was careful not to touch her.
When I went home I asked him, if I could borrow his jacket for the way home and give it back to him on monday and now it is in my car.
I had never checked a jacket at a club before and didn't know how to go about it; he came over and asked, "Can you do it? Is it okay?" but with a gentle smile, while touching my shoulder.

I know I am very awkward and him being so nice probably doesnt mean ANYTHING. But you need to know, that I am not very pretty. I recently lost a lot of weight (50kg/110 Ibs) and men were never nice to me before. I am still fat tho and have a lot of loose skin.
It just felt so nice to be acknowledged that I cant stop thinking about it.
He also drank alcohol, but didnt seem very drunk and I never drink.

Now I need to give it back on monday and it is embarrassing.