When disaster stricks! Having to cancel at the LAST moment.

To me it was most important that you notified him as soon as you could. Most hobbyists understand that shit happens. I would get a plan B and be happy to reschedule...
That is ALWAYS better than a NCNS.

Stuff happens,and your offer was very nice,I bet he's happy that you cancel rather then him showing up and then it comes!!I'm sure he would have loved a reduced rate bj session though since it was minutes before his scheduled time