Engine Oil Light

Hello everyone I have a problem with my wife's friend 2004 Impala LS 3.8. About a month ago I did an oil change on her car which I went a little bit over the 4 1/8 or 4 1/4 qtrs of oil that requires drove it around no problem (by the way putting more oil can cause any problem?). So know her ENGINE OIL LIGHT comes on everytime she starts the car and it goes on and off and it will go away after a while can anyone tell me what the problem may be or its because I put more oil than I should not have or oil sensor going bad and there's no engine light coming on.

Thank you

1st it takes 4 and 1/2 qts with the filter, 2cnd is the oil pressure lite or level lite?

O.k oil level is fine and its the little can with oil drip that comes on which I believe is the oil pessure icon. So what thats this mean its something wrong going on or what's causing this and what can I do to fix the problem

You need to have the actual oil pressure reading taken with a mechanical gage to confirm there is no internal problem, if good the sender is bad or the wiring to it.