Cracking of straight wall pistol cases is fairly common with cases used for multiple reloads. Seems to me cases with knurling (used to prevent bullets from seating deeper in the case under recoil) seem to crack more often.
Factors include pressure of load, size of chambers, how small a piece of brass is being re-sized, amount of case mouth bell, brass hardness, etc. A crack in the upper body of the case is not a big deal, from a safety point of view, and should not be confused with a failure in the web, which is a whole different matter.
When loading straight wall cases for practice handgun loads, I reuse them until the primer pockets get loose, or the cases split. For some reason, it seems more common in nickel plated cases.
Larry