I was travelling on a crowded bus. Someone suddenly ran into me and touched me when the bus stopped suddenly. The man said sorry to me. I did not get angry because I could see there was an auto accident not far from the bus, and then I said this,
that's alright
Was it polite for me to say it? If not, what shall I say? Or are there any better expressions when someone ran into you but you are alright with it?