Is the red light the power light (in which case it should always be lit if you have power applied) or is it the charging light (in which case, if there's no phone on it, there's something wring with it, which would probably be the reason it's heating up, if it's the pad that's heating up).
If the pad is more than just warm to the touch if there's no phone on it, there's something wrong. If it gets warm while there's a phone on it, that's normal.