I have only seen this with the PVC anime statues, I have never heard of a resin cast doing that. Usually it is related to heat in the environment that the PVC statue is in, and if it has any really top heavy gear/stuff/weapons/boobs. I have several resin statues that I could not possibly begin to imagine them bending as resin is a hard material, all it can really do is break. My wife is a champ at breaking resin hair on anime girls, all of the broken parts did not bend at all before snapping off.