In october last year I bought 4 tires for my car and at same time got the alignment and balancing done. After that the steering wheel angle was a little bit crooked, as the car neither glided to any direction on its own and after observing the tyre wear being normal I let it stay that way. But now after I have done more than 6000km decided to rotate the tires as instructed in the manual. After rotation to my surprise the crooked steering became straight again. So is this normal or could it be a bent wheel rim ?