Why is my steering wheel out of alignment?

[Mike10]

What causes a steering wheel to go out of alignment ?

Last week I took my 2007 Explorer (95,000km / 50,000 miles) to the Ford Dealer for an oil change and tire rotation. They also replaced the right rear axel under the powertrain warranty.

Leaving the dealership I noticed that the steering wheel was out of alignment (now at 1 o'clock).

My tires are all at exactly 35psi and the truck doesnt pull to either side when braking.

Could the tire rotation have anything to do with it ?
They tried to sell me Power Steering fluid service, rad service and transmission fluid service - could these have anything to do with it?

I'm sure its easy enough for the retailer to centre the wheel for me, however I want to know what caused it. Could it be parts failure, what should I check?

 

[ZO6_Vette]

Did they do a wheel alignment?
Usually that is why steering wheel is off.

 

[Mike10]

No Alignment was done. Just an oil change, tire rotation and the rear axle replacment.

 

[michael loibl]

could be that one of the formerly rear tires had a shifted steel belt which was not noticd on the rear. now that it is on the front it could cause slight crookedness... however you would most likely also notice the steering wheel wiggling very slightly while cruising straight around 20-30 mph. I would try swapping one front back to the rear then drive it and see if it went away. then try the other side.