Tire Cupping?

I took my Escape in for a possible U-Joint (vibraton above 40mph) issue. My dealer says the rear tires are cupped. I am not buying his diagnosis for a couple of reasons:

- after 2 decades in the business - although no longer inthe business - the only tire cupping I ever really saw was due to alignment issues, and my car was aligned in the spring. It was only slightly out before and now is bang on.
- These tires were on the front but rotated to the back 3 weeks ago. The noise suddenly appeared on Monday of this week. I had driven over 1000km since the tire rotation including 2 long highway journeys and no vibration until now. Also no vibration in the steering wheel before or after the rotation
- they simply do not feel cupped when you run your hand across the tread blocks. I will check with a straight edge when it is light out.
- I am getting driveshaft noise when cold (a moaning that gets faster, but quieter, upon initial acceleration)

He says I need to rotate every 10,000km (I rotated at 15,000 and 25,000) and the best solution is to leave them where they are, and let tread wear take over, but keep rotating. My thought is to move the rears back to the front and if the vibration is gone, leave them there forever and only ruin a pair of tires over the next 18 months or so. But I'm still not buying his diagnosis. I know Escapes eat wheel bearings but do they eat tires too? My service manager said they do....I thought that was just the old I-Beam F150s???

I have the 225/65R17 Michelin Cross Terrains. At 26,000km they still have 9/32" left and they rock in the snow! I have been told, of course, that since the issue is with cupping there is no warranty on the tires.

I do plan on visiting a Michelin store this week for a second opinion, but I thought I'd check with the real experts first.