Generally speaking, if nothing happened, then nothing happened. And if something happened, it has already happened and will be obvious. Overfilling is most likely to cause problems at higher rpm. I know the small engine is slightly more sensitive. But we've had careless lube guys to forget to drain the old oil and install 6qts of new oil. The customer would leave. If they were a conservative driver, they might not notice for several day until they have to rapidly accelerate. Then it smokes like a burning oil well. They come in in a panic. We drain the oil and properly fill it. We drive it about ten miles to clear the smoke and to make sure there are no obvious problems. The manager puts in writing that if a problem occurs within X amount of time or mileage, the shop will make it good, they offer the customer a few free oil changes or a free detail for good will. And the customer is on their way. So far no one has returned with engine problems. If there is any damage, it has always been evident immediately. I'm going a long way around to say don't worry. Just make sure it never happens again.
