Thats the same story I got....i dont see how one test sheet would take so much heat out that it needs to warm up. some serious software fault
The time it takes for warm up is to stabilize fuser temps. You can cut the warm up time considerably by going into Utility - User Settings - Common Settings - hit next a couple of times until you see the options "Fusing Stability (Quick Start)" and change it from Image Quality to Speed. There is also an option for Fusing Stability on Mixed Media which if set to speed will not stop at all between different weight sheets. The caution here is that the fusing temp may be slightly different on the first few sheets of a job as it stabilizes once in production, but it cuts that warm up time down by about 70%.