Yeah, the pic that Dan posted is from me and my Superman PF is definitely leaning. But it is due to the pad beneath the base on the cape side. The pad on that side is worn down and compressed by the weight of the cape, causing the left front side of the base to be raised.
A thorough inspection of my piece revealed no warping of the metal rod, peg or the knee area. Both feet sit flush on to the base without any gaps from the weight of the cape. I put in new felt padding around the compressed pad to stabilize the base with all the pads making contact with the pedestal. So it definitely looks more upright. But I think using the thicker, clear vinyl pads will straighten it out even more since it is a lot more durable and doesn't give like the felt pads that I'm using. But we are talking about fractions of a millimetre here. It must be the humid and muggy air here in Singapore.