Does anyone with the OEM Bridgestones experience what I experience every morning when I take the car out for the first time?

I get what feels to be a flattening of one of the rear tires, so the car rides as if I have an unbalanced tire for the first 2-3 miles. Then it goes away.

It's a MY2002. My first set of OEM's that were on the car when I bought the car new in 2002 did not do this. The replacements do. I live in the same city since I had the car, so we can rule out climate or temperature as a reason.

Does anyone have any explanation for this?

Thanks,