Remove the chain. take a matchstick and some blue tac. stick the match onto the front mech so that it just misses the chainwheel teeth. spin the cranks.
As the cranks are spinning freely, and not under load, you'll see if the chainrings are bent. try it with both rings.
If its not bent chainrings, it'll be flex. I would recommend you upgrade to a SHIMANO set of cranks with an external BB, no chance of flex with them