It's only the dust cover that's come off. The bearing still seems fine, otherwise, but it could be a sign of a lot of movement between the inner and outer race. I won't know until I get it out.
I haven't measured the head speed, but I think it should be somewhere between 3000 and 3300rpm in my 2 idle up settings. This would depend on how efficient the motor is. So not too insane for a 450.