See if you can get the dealer to swap pedals and see if that does the trick. Being an intermittent problem, your dealer probably does not figure he can find the problem easily - and he's not willing to try to keep a customer happy. I don't think I'd buy from that dealer again if I had a choice.
I've had my machine for a year and a half, and the only problem I have is that my foot pedal will get dust inside and then my speed will start to vary on me. The first time it did this I wasn't sure what the problem was, but picked up my pedal and blew it out - and then it went back to working properly.