Hyundais are notorious for trashing valves when the belt fails and the cost to repair the damage is somewhat expensive at best but if pistons get broken the cost is somewhat outrageous. I have replaced more Hyundai timing belts than I can count, several with over 100,000 miles that were running fine pre and post replacement but on the other hand I have had several show up with stripped belts and all had internal engine damage. One was hauled off for scrap because the repair estimate was far beyond the value of the car. If mostly driven in stop and go traffic it would be advisable to play it safe. If the mileage is mostly commuting the belts have a greater life expectancy but if the dealer recommends immediate replacement and the belt fails there may be no warranty.