OK, I checked the spare and it is quite obvious on the other side of the tire, definitely undulation.
I don't understand how I missed them on the tire that is on the TT, I have looked at them numerous times in the past month and never noticed it. But I checked and sure enough the same indentations are on the opposite side but not as noticeable. Because there are 2 within 6-7 inches of each other, it makes it look like a bubble between them.
Thanks all for the wisdom, wmtire you know your stuff! I have never heard of undulations in tires before but then again, I never read much about tires until we got the TT...
here are some pics of the spare: