Wow, I've never seen this before. Bubbles in porcelain. Definitely from the original manufacturing.

322910448624

definitely a 2nd .. ...

Maybe it got heated up on the backside some time in its life? Chris

Considering the other side is flawless, I don't believe heat had anything to do with it. I believe like anything else, the surface was contaminated before the porcelain was applied and as Randy said it was a second so it never got hung.

...I guess he made an error in his listing, as he's ended it prematurely for that reason...odd that he hasn't yet corrected the error(s) and relisted the sign...