Yeah, bark will slip in the spring but if its dry in the summer it can stick. I wouldn't worry too much about a few minor violations though, the thing rings mean you have backup fibers near the outer surface. Should be just fine.
I still have an old piece of hackberry I scavenged from a city tree limb lot. Bark was stuck and I drawknifed some off, never finished the job though. That piece has to be at least ten years old.