No, it's a pressurized tank so the gas doesn't go bad.
Supposedly the car will know when it's been in there too long and will automatically make the ICE run through the tank, but it hasn't happened yet and the gas has been in there since the first of the year. Here's a link to an article that explains how the system works:
http://www.plugincars.com/putting-th...olt-69473.html
I try to run the ICE at least once a month until it warms up to keep the engine lubricated, but I have to make it do it since my normal commute of 38 miles isn't long enough to make it kick in.