Today I started my MX5400 and it fired right up. The tractor sits outside and it was about 12F and has been in the single digits the past few days. About 20 minutes after starting, the RPMs slowed, then revved several times then the engine died. In the fuel filter the fuel looked "slushy" - not frozen, but not clear either. I let it sit about 10 mins and tried again. It fired right up and ran the rest of the time. The fuel in the filter cleared up as well. Was this the dreaded gelling of the fuel?