I've got several bucker guitars that do this. I notice a minor change in the sound. It could be enough to bug some people (like me) so I just turn way up and don't really pay attention to it.
The only thing I've thought to do but haven't done yet is to wedge something in there to keep the pickup straight. I'm not sure what an official fix might be. All the screws are straight so it could be a cable tension thing. If the wires going to the pots from the pickup are doing it then maybe there is a way to move some of that wire into a different position so that it doesn't affect the pup angle.
"No Tele For you." - The Tele Nazi
Ha! Tele-ish now inbound.