Purchased this CD 129 recently from an eagle-eyed collector. Up until now, all the CD 129s I've ever seen have a standard curved dome (on the left in the photo). This one, however, has a circular indentation around the top, sinking in about 1/8". It's very uniform and seems deliberate (it doesn't appear to be an underpour or a sunken dome).

Mold and date code is 5-59: (1961 production). I'm curious if anyone else out there has seen one like this - maybe they are pretty common and I've just been missing it all these years??