This incident went down last Thursday at the home of Ann Patton in Ocala, FL -- where the homeowner says she saw something on a surveillance camera that led her to believe a bitter UPS driver got petty revenge by spitting on one of her packages.

UPS was apparently scheduled to come by that day and pick up a separate package that was supposed to be ready for the driver ... but wasn't. Patton tells us she was never notified of any UPS pickup, so that's why nothing was left out.

Anyway, Patton claims when the driver arrived and realized what he'd been sent there to get was nowhere to be found ... he tried getting back at them by picking up an Amazon package that'd been left earlier in the day and spitting on it ... at least that's what happened in Patton's eyes, who caught the alleged spitting on video.

Of course, the Pattons freaked and called up UPS in a rage ... saying they were told the driver would be canned, but claim the company refused to replace their Amazon package. Naturally, there's a lot to be concerned about if it spat on ... COVID comes to mind.

Now, as for UPS ... they have a slightly different version of events. The company tells us that, yes, they did fire the guy -- who was a temporary holiday driver -- but only did so out of an abundance of caution, because in their eyes ... it's not clear if he spit or not.

Decide for yourself ... UPS said it looked like their dude mistakenly thought it was the package he was there to pick up and was simply following protocol by blowing on the label to clean it off so he could apply the UPS label. They think when he realized it was the wrong package, he just left.