My gas stove; revisited.
After posting a poll here about how long it takes to warm up the stove, I called a service company and had them come out and take a look at my stove. They found some problem and fixed it. Thank you, with out your comments I would have never called anybody. The thing was I called the manufacturer customer service prior and they assured me that the stove was working properly. So, I was all sure that half an hour is the right time for warming up. It takes only 10 minutes now to warm to 350 deg.
You are what you eat.