That is called "post flow"...it will stay on for a few seconds after each cut to more efectively cool the consumables......when you trigger the torch during this post flow it immediately interupts the flow in preparation for the next cut. It is perfectly normal!
Feel free to post any questions. You have one of the best air plasma systems available....and we''ll be happy to help you out. I own a Powermax30, Powermax45, and a Powermax1000.....I use the 45 and the 1000 on a small cnc machine, and also with hand cutting applications.