Drooling

Once a month, I always give my cats their monthly doses of Revolution. Of course, they don't like it and try to run off to get away, no matter how calm and soothing I make my voice.

Smokey does something a bit differently in addition to trying to get away. When applying the Revolution, I have my one hand cupped under his chin to gently keep him from moving his head away. After the medicine is applied, I'll notice that my hand is covered in drool from his mouth.

It's the only time he ever drools, and Casey never does it (Chessie never did either). Is this something I should be concerned about, or is it just because he's upset at having to go through this?