doubt you "lost" a tank of fuel. how do i know that? it can only get "lost' in 2 places: into the motor or onto ground. if a tank of fuel went into the motor your post would be titled along the lines of "HELP!!!! started motor and both connecting rods blew out thru the crankcase assembly." your motor would have suffered hydraulic-lock and permanent terminal damage.
other "lost" fuel area? the ground. four gallons of fuel under the bike noticeable to put it mildly. highly doubt that happened.
here's what's going on and NO on the "possible fuel pump earth issue".
1-your frame/tank was very warm. you filled it with gasoline that averages about 50 degrees fahrenheit when it's pumped out of the in-ground tank. the fuel expanded rapidly and quickly and the venting system admirably performed its job puking said fuel onto the ground as you rode home.
2-your cap vent not functioning properly. check it.
3-fuel pump twin O-rings leaking.....fuel seeping out of lower left frame spar at pump. check it.
4-tank vent failing which is EXTREMELY rare. if faulty replace with factory part # P011502A8B
5-refine your fill-up procedure. either fill up at home from container AFTER both motor and frame have cooled to room temp.....OR fill-up when first leaving on a ride prior to motor and frame heating up.
and think of it in these terms: look at a conventional bike gas tank.....it's steel, a poor conductor of heat....and ABOVE the cylinder heads. virtually no heat transfer from motor to tank hence minimal fuel expansion upon fill-up. now consider the XB tank which is the frame: it's aluminum, it's huge, it transfers heat easily and it encapsulates the hottest parts of the motor....the cylinder heads. in all honesty it's amazing they don't puke more fuel on a summer day fill-up than what they do.