No tire rotation. I would do that myself. The wheels have staggered widths, right? I think I'll rotate my tires, swap left to right, if they are not directional that is. See if that makes any difference. I could inspect the tires a bit while they are off the car, as well.

 

I know you said you check the pressure once out of storage, but have you checked it recently? I know my Conti's get flat spots from sitting over the winter, but after checking pressure (pumping them back up) to 34 and running it for a bit it goes away.

Drive from Minneapolis to RA and back should alleviate flat spots from sitting unless pressures are too low.