I think it depends on the situation, but by the sounds of it I think you were quite entitled to an explanation and apology. I'm not always great apologies myself though. Like, this morning I was really late for an important meeting. I was super nervous, had done loads of prep work, showered etc, and sat down to try and plan as much as I could how to deal with my nerves in the meeting. I got totally caught up in my own head and didn't realise how long I'd been thinking and next thing I know I'm an hour late. I barely apologised because I was so embarrassed and didn't know how to explain my lateness. It wasn't me being impolite- more socially inept. I guess T's probably shouldn't have that as an excuse though.