I have seen that on 44 Rem. Mag cases, in the past on once fired Speer brass, I believe the brass was brittle and the area where the flash hole is situated was broken when the primer was inserted and ended up in the casing. Yes I would say, either save for reference or like someone suggested use it for a cleaning rod guide or discard it. This not a common occurence I have only seen it once in 40 yrs.