Zero Turn Mowers

i recently purchased a Husqvarna RZ5424 zero turn mower. When I first get on and start the mower, I have no problem. Little Choke, turn the key, fires right up. If I shut it off after mowing for some time, it will not start back up until it cools completely down. No matter what I do with the choke or anything. If the mower is hot, it will not restart. Brand new gas, etc. has about 6 hrs on it. Kawasaki engine. Any help would be appreciated.

Andy