Bottom line is, if its to Caley's advantage it will be done. This is done all over the world,any small advantage will be taken, you quite often see teams watering the pitch at half time aswell, to help speed the ball up along the ground. Football is all above fine margins, if caley did let the grass grow longer then fairplay, they noticed celtic like playing a quick fast game along the deck.
As a side note, Man City don't have any Tactics boards in the Away changing room, if the Away team want to use one they must bring their own. Even big clubs like small advantages.