I'm happy for your sake if your rear main seal is fine. Its a simple enough job but due to having to take everything apart the job turns into a huge PITA.

There wouldn't be any indications, changes in oil pressure, or CEL lights if the engine is overfilled by about one quart of oil. What normally happens is that the oil level is a little higher in the oil pan and a lot higher inside the valve covers. The valve cover gaskets are usually dried out at the upper levels so quite often your excess oil will begins to leak from one or both.