Yes, the seal making that mark is very normal. Lucky there isn't a ridge there. There often is. The replacement will be a different type seal. Much better design in form and function. Their sealing surface is mm's long. They don't wear grooves into the flywheel for it.
The flywheel teeth came machined like that.
The piston ring gaps often came way out of spec too large from the factory. Some guru's have you check piston ring gap for cylinder wear. That will get you a lot of work since they very often came brand new with ring gaps that were way out of spec. I have measured at least a dozen sets of brand new matched at the factory nikisil cylinder/piston sets. ALL of them had way over spec too large ring gaps brand new. They sure would run a lot better gaped properly!