ok, now I call BS on this whole situation.

ITA matrix and delta.com are now both reporting that there are 4 economy "V" class tickets available at the cheaper price on multiple different departure dates almost exactly 24 hours after they were replaced by "X" class availability (again, ONLY on the dates I tried to book yesterday)

so I am back to believing that Delta was manipulating fare bucket availability due to me searching and adding them to my cart to checkout

VERY Little chance that I accidentily ran into a cached fare issue on multiple different departure dates only to have them revert back today to exactly how they were before

Too many coincidences with too few variables to be random...