So I emailed and he said sorry he had been in a meeting and forgot he had a meeting with me.

Should I take this personally?

He gave me 21 out of 22 for an assignment 1 month ago.

Don't understand. Seems quite unprofessional.

This happens! Often meetings slip supervisors minds, and I have on occasion gotten the date completely wrong myself.

I wouldn't take this personally if it has been a one-off, remember that supervisors have a million things on their plate, you are just one of em. They are also human and have bad days too.

Hi Timmy, yep, happened to me but only once. I was peeved because I had travelled 15 miles to the university for the meeting and then 15 miles home for nothing. If he has apologised I'd imagine it was a genuine error. I'd be peeved if it happened regularly but it could be a once off. Don't worry. I highly doubt it's anything personal.

No, this kind of thing happens occasionally unfortunately. With my previous supervisor, it was usually lateness as a result of delayed trains...

Replace your idea of 'professional' with 'academic'. Academics get so much piled in their direction, they often get double or triple booked...or get stuck in meetings that over-run.