So you're just waiting for your new regulator, wondering in the mean time what has been going on? Seriously, there's no need for confusion; no gasoline whatever should appear at the vacuum port of the regulator. The part is defective, and I doubt very much you or your car is responsible for its demise.

Just the same, because I can envision somehow where a blocked return might allow unplanned pressure on the vacuum diaphragm, I figured I'd suggest the blow through the return line. I doubt it though. But my bet is the regulator was not responding to the loss of vacuum so much as the motor was responding to the addition of air unladen with fuel.
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Art Benstein near Baltimore Crrrrazy Ray's!