Mike - yep, we're confusing terms. Now I understand what you mean by "hat", it's the stamped metal cap (mine's black) that sits between the strut mount and the bump stops (what Thomas calls "snuggers") and actually caps the spring. Above that part there's a strut mount, I thought that was what folks were calling the "hat". From here on out I'll call it the upper strut mount. It has 4 bolts that secure it to the chassis.

I did check the rotation of the bearings on one of the strut mounts and it seemed smooth and stable. I didn't check the other (just didn't think of it). That might be the problem, I should be able to check it without removing the strut. I tested the driver's side bearing yesterday before re-mounting it.

Thanks to both of you for the suggestion.

 

I suppose it could also be I didn't mount the springs right during re-installation and they're "creeping" into position. I'll check that too.