but instead it ran great, like nothing was ever wrong.
Sadly, that's indicative of the feedback carbs. Something is on the fritz, but the computer doesn't know what. That's not a good sign. Personally I would AT LEAST pull that sucker off and install a non-feedback version.
could it have been air/vapor locked?p
Vapor lock doesn't occur on vehicles with electric fuel pumps.
maybe a piece of something in the carb?
Peices of something in the carb don't just up and dissapear. Stuff can get in the carb - I've even seen it happen. But if that's the problem, then it's going to come back.