I've written about this same premise quite a few times in the annals of Fail Blog, but any time your boss is accusing you of doing something despite there being no evidence—and especially when the evidence shows quite the opposite—it's more than likely that they're just projecting their own personality flaws, predispositions, and hidden thoughts. Basically, they're just admitting that if they were in your position, they would be doing the same thing they're accusing you of.