With that mileage, it causes no problems whatsoever.

 

There is the possibility that it was incorrectly mounted. On hi-po tire/wheel combos the best method for mounting the wheels is to use a mounting paste on the rim and a nonaqueous tire lube on the tire (anything other than an engineered product designed expressly for mounting tires is BS) well in any event, if the tire is not seated correctly on the rim (and visual appearences are no guarentee) it will exhibit symptoms similar to flatspots on the tire.

On average tires experience less than 1% in defects (then again there are like a million billion kajillion tires produced every second) but anyways alot of tire problems can be traced to incorrect mounting procedures.

Runout may also be an issue and can be corrected by match mounting

Ask how they did the work (just to narrow it down)

A. Did they use an approved tire lubricant (some are water based - old school stuff that leads to corrosion down the road - but the good stuff like I said is non-aqueous)
B. Are the rims lug or hub centric? and if they are lug centric, did they use a spring, cone and pin plate to balance the tires.
C. Does the balancer automatically measure runout and or force variance (the second one applies a roller and a moderate amount of force to the spinning tire)
D. How was the wheel mounted back on the car (best method would be hand or very light use of an impact wrench at the lowest setting, then tightened in the proper pattern using a torque wrench set to the proper torque or about the mid-range if the manufacturer offers a torque range.

If they followed these steps then you can pretty much eliminate operator error and zero in on the tire as the culprit if in fact that is the case.