Shut the water off, drain down the tank a few gallons, then find the correct socket to remove the anode rod. Then, use teflon tape and wrap the threads on the anode rod along with teflon thread sealant and reinstall. Turn water back on to see if it still leaks.
You can actually have tech service come out and inspect this @ no charge to you. They cover this under the warranty. It might be a defective tank. If so, they will replace the water heater @ no charge to you.