And ask them how to un-root the phone. I've found too many do this and then turn the device into a brick or forgot that not only can you root, but you must be ready to un-root the device.
I rooted my Galaxy S3 when I first got it, and it's been fine ever since. The only problem so far is that I received an update notification saying there was an update for Android. I downloaded it and tried to install it, but had a problem when it restarted to install. It went to the screen that it gives when you first root (the one where you pick the rooting package and get it to install). Then it shows the Android robot dead. Fortunately, restarting again allowed it to revert back to the way it was. But how do I update the software?