is my old crt flickering or is it just me?

50 Hz is definitely slow enough for a wide range of people to notice flickering. CRTs always flicker, but at 72+ Hz few people notice it.

You need to set the Screen refresh rate to something higher than 60 for 15" monitors and higher. The larger the monitor the faster the better. It has to do with the time it takes to redraw the screen, and on 17" or better 60 times a second is just to slow and your eye will notice the changes in energy being refreshed. It could also be because a fluorescent lighting fixture is near with its odd/even ballast refreshing in sync to make things look weird. 85Hz is what it takes for me to be comfortable with a CRT.