Maybe possible, but very unlikely. I have never seen it.

Rims are made as an extruded channel, so every inch of the circumference of the rim is identical to every other inch. It is possible that the machine used for extruding is damaged or worn and a defective part found its way through without being noticed, but I have never heard of or encountered this. Generally QC checks would catch minor inconsistencies than the machine fixed before continuing to extrude rims. The chance that the machine was damaged such that a small segment of one rim was different than the rest is not plausible.