I rotated the tires with my last oil change.

[no_hypocrisy]

Do I need to balance and align now?

[Arne]

1. Only if the steering wheel shimmies.

[kacekwl]

2. No

Unless you had a problem before.

[no_hypocrisy]

3. Thank you all!

[CanonRay]

4. Unless you hit a curb or big pothole

The alignment and balance should be fine.

[A HERETIC I AM]

5. What happens when you let go of the steering wheel at 40?

Does it want to drift one way or the other? If it is properly aligned, it should go straight or drift slightly to the right because of the crown of the road.

Also, does it track straight ahead when you hit the brakes and don't hold the steering wheel?

The last thing could be a result of a problem with your front or rear disc brakes, but could also point to bad alignment.

But as others have suggested, unless something drastic changed like hitting something hard, you should be fine.