Heehee. No, it's intentional. There's no way it isn't intentional. For anyone who doesn't know what it is, it is in fact a "virus" that your pokemon can catch from physically attacking a wild pokemon which has it. I'm not sure of the odds of such an occurecne, but this so-called "virus" is quite helpful. Any pokemon currently afflicted by it will gain boosted experience. However, one a pokemon catches it, it will go away in a day or so, so start training fast! You can transmit it to your other pokemon by simply placing the infected one in a box with your others, where infected pokemon remain infected for as long as you like until withdrawn. In this way, the virus can theoretically be kept alive almost indefinitely, but bear in mind that once it wears off a particular pokemon, that pokemon can never get it again.
In short, it's too complicated to be anything but an intentionally programmed aspect of the game.