I've seen a few damaged wheels before but that looks like metal fatigue or a manufacturing fault. They certainly weren't very strong if you only spun it and didn't even hit a kerb.
I think Compomotive ought to replace all 4 ....... and soon!

Dymags had a reputation for doing this as they tried to make them too light and then they disapeared altogether!
Let us know how you get on!

 

Compomotive have got the wheels at the moment!!