Car question where does it belong?

[footfootfoot]

We've put 97,340 miles on our '04 Hyundai Sonata GLS. No problems so far but would have liked the info about how you need to pull the engine to replace the platinum spark plugs when I bought the ride, but whatever.

So we are creeping up on the ned of the warranty period and for the last 10k miles we've had a very slight, but now noticible, vibration problem which has been hard to get a diagnosis on. I'd like to resolve it before the warranty is up if it is a warranty issue and not a wear and tear thing.

Specific symptom: vibration in front end from 20 mph to 28mph. Now the vibration continues up through all speeds.

Wheels are balanced and rotated, snow tires are swapped for summers. car is routinely aligned. Vibrations happened with either set of tires. When the snows were pulled there was noticible scalloping on them. Our tire guy said that could have been from a number of causes, but couldn't be certain which one. Our regular mechanic said he thought the low speed vibration could be a bent axle, but he couldn't be certain. Both of them said to wait until the problem got worse...

Not wheel balance
Not Alignment
Not bad tires

I'm making an appointment at the dealer tomorrow. Someone suggested shocks, but the car rides fine and the 97k miles are almost all highway miles. I'm curious to see if the tires are scalloping again and if so, what would make them scallop if the alignment is good and the shocks are good? I need to check the service schedule and see if shocks are recommended by now.

Any of you have any thoughts on the matter?