Well, you could have, but who knows. If you're not seeing leaks, you probably don't have any seal issues. The other issue that too much oil can cause is when the crank splashes in the oil in the pan, which makes the engine shake and can whip the oil into a froth/foam that won't circulate properly and starve parts of the engine for oil.

Drain the oil, put 3.5 quarts back in, and assume all is well. Not much else you can do. Tell the shop they damn well better put 3.5 in next time, if you even go back.

Brent