Hi Jeff, I'd expect you to be fine. I've had some serious wear and tear on the chain stays and usually this area is quite beefy. Pictures would be most useful here, but I would not sweat it.
Bit of a wacky idea but if you are really worried, lock the rear end into a trainer and manipulate the crank area, hold the rear brake and have someone clip in and deflect the frame, see if you get unusually large movement and put your ear against the frame to hear if anything is going on in there. Don't go crazy though.
Usually these things are cosmetic.
Perhaps a picture with a straight edge rule across the top so we can see the cut with some perspective/size.