[batman1425]

Sounds like a cut in the threads somewhere making a bulge.

Could be that you just didn't notice it till the move, or perhaps there was a small damaged spot that was made worse by the removal and installation from one wheel to another?

I'd inspect the spot of the bobble closely for damage.

I had this happen once with an older set of continental tires. The rubber around the bead was getting beat up from installation and removal and peeled off in a few spots. After that, whenever I mounted it up, the bead wouldn't sit right in those areas and it would present as a wobble or bulge. I ended up just tossing it. Not worth a broken collar bone or dental work from a crash.