It is very common to have spotting and breakthrough bleeding while on birth control, especially if you recently changed prescriptions or started a new pack. Make sure you take your birth control pills at the same time every day to reduce the chances of this happening and that you do not miss a pill.
Yes it is very common it as actually one of the effects listed on the box. It is more common in the beginning when you first start taking the pill. Once your body gets acclimated this problem should pretty much go away. However always check with you doctore just to make sure.