No this is not a stovepipe. A stovepipe is when the ejected case is not thrown with enough force, and it gets caught by the closing bolt. You will see the open end of the case sticking out the side of the ejection port and that case prevents the bolt from fully closing.
Check the other cases you fired for heavy marks from the extractor, as the gun may be slightly overgassed. That is, the bolt was trying to pull the casing out before the pressure in the case goes down enough to allow the case to unstick itself from the chamber wall.
You aren't running a suppressor are you?