The ABC's of mole irregularity
Assymetry-if the right side is not the same as the left side and the top the same as the bottom
Border-if it is jagged
Color-if it contains more than 1 color
Dimensions-if the size changes
These are Definate reasons to have it looked at but more importantly if you were concerned enough to post on here you should get it checked! The best course is to make sure that it is nothing if it isn't and to catch it early if it is!