Not everytime. Just when enough time has passed to allow the area to absorb enough heat to cause gas breakout. If you have a blow out party [^] and the faucet is opened frequently, no problem. If you dispense a glass and decide to take a nap after enjoying [|)], then after waking you dispense another beer - you will probably get a shot of foam. If you can live with a beer chilled system, all the naps to ya!
Scott Zuhse, Instructor
Micro Matic Dispense Institute