Leaving VP in tank bad?

and here comes the naysayer!

Recently, I left a couple gallons of VP U4 in the tank of my '03 GSXR600. One week later, I was running the bike at Grattan and it really started to run BAD.

After pulling the motor from the bike, and checking valves, cam chain, leak-down, etc. we felt inside the throttle bodies. They were very gummy inside (Sticky is more like it).

After a thorough cleaning of the throttle bodies, and removal of remaining fuel from the tank, we added some pump gas and she ran like normal again.

The fuel was purchased new, poured from a freshly opened can into the bike one weekend, left in my garage one week, and ran the following Saturday with the problem.

Things to note: The weekend the fuel was purchased was very wet and humid. The week it was in my garage was also rainy and humid. The following weekend it also rained. Not sure if that has anything to do with it but the fuel was definately "gummy" after one week.

I have left VP U4 in my bikes before, for longer periods of time without any real problems.