The fuel in the tank is constantly being recirculated. It heads for the injectors and is returned to the tank at a pretty good flow rate. The fuel on the way back is warmer then the fuel on the way out. It is conceivable that the tank is 20 degrees warmer than the ambient air. This would be especially true if the level of fuel in the tank is low.

I wouldn't be too concerned about it if you consume a tank of fuel within ten days or so. But, if this time is exceeded, and the vehicle has quite a few cold starts, the warmer fuel could present condensation issues.