None as you are in a dungeon. To my knowledge, no one has ever been banned doing this, and I know people (my self included) who have left it on for 3 - 4 days straight.
Will probably be patched in clan citadels update i reckon as jagex won't want people getting easy 99s in a skill that is normally expensive/hard to train.
OK, Just a little pinprick-There'll be no more-ah!