Ditto, I took his discrete math course at NCSU in 1998. It was mainly taught by Tiffany Barnes day to day (who was also nice and a great explainer), but Bitzer was often present and always smiling and jovial.
I really regret having spent so little time interacting with my professors though. I was one of those kids that spent the least amount of time in class possible, almost never going to office hours, aiming to get the course work out of the way asap so I could "have a life". So much wisdom and life/industry experience was concentrated on that campus and at my fingertips, but I totally took it for granted. Seeing his obit amplifies this feeling; I wish I had cared enough at the time to meet and know the guy.