Matinee camera rotation messed up !?

I’m trying to make some matinee cutscenes in my level, but for some reason the camera rotation on the Z axis gets messed up - for example, I try to make a slight turn of the camera, like 10 degrees on the z axis, but instead I get a full 350 degrees rotation in the opposite direction… Any camera in this particular scene does this and I can’t figure out the problem.
Any ideas?

Selecting the camera at the first key, reading it’s z rotation value from the properties tab and entering it manually in the key, then doing the same thing for the second key fixes it, but I don’t get why it happens.
The keys in Z rotation are created with values in hundreds/thousands. At least it’s not happening every time at this point, only occasionally.