Is OTHER wrong in the post ? POST : So this happened a few years back, and I no longer live with this roommate (not because of issues, he moved away to pursue a master's)

One morning before work, my roommate was taking longer than usual in the only bathroom in the house. Normally we had it down pretty well so that I was done in time to catch my bus. But that day he took an extra 15 min. 

Because of this I decided to knock on the door and politely remind him that I need to get ready for work. I may have used the words "hurry up" but I don't think my tone or intention was aggressive, just informative. 

When I knocked and said this, he blew up on me. He opened the door, started yelling, waving his razor and saying "you don't knock and bother someone while they are in the bathroom".

I was a little intimidated, but I just held my ground, said that I was going to be late to work because of him, and I don't appreciate being yelled at.

I come from a house that had two bathrooms and 7 people living in at (at least at one point). Knocking to let someone know you need the restroom (either if you couldn't hold it or you had to be somewhere) was never an issue. So I didn't think it would be an issue in a house with 3 people and on bathroom. AITA for knocking and asking someone to speed it up a little?