OOPS! Overlooked the "under warranty" part of your original post.
If this happens again, you have an abnormal condition. A/C systems are well engineeded and "freeze ups" indicate a problem.
Here is some FYI stuff for your benefit as the service mgr & service tech should be trained on this.
One of my 'tweener jobs was a service mgr. for a new car dealership. On the occasion I had one come in for this problem, I always wrote up for the service tech to check for leaks first. If no leaks found, then I had them remove the charge to 0 psi and recharge to factory specs. (No need to pull a vacuum unless a leak was found and system opened). Then check for proper operation of the low pressure compressor cycling switch. If the switch is cycling at proper pressures and compressor is "short cycling" with full system charge, (high side pressures would also be out of range at this point) this would indicate there's a restriction in the fixed orfice metering device. System would then have to have charge removed and opened to see what was causing the blockage.
NOTE: Vehicles are now considered to be "critical charge" as most operate with less than two lbs. of refrigerant. Just a few ounces can make a huge difference. Refrigerant charge must be weighed in to the ounce. My refrigerant scale weighs down to 1/10th of an ounce. Occasionally one will come out of the factory with an improper charge. Hopefully your dealer's techs have been well trained and should know this.
Cheers and Good Luck!