Fuel line leaking after fueling truck up

Here goes guys and gals, I’ll try to make this short and sweet. I installed a fass 140 a few months back and completely bypassed the hfcm on my 2007 6.0. I removed the factory hfcm but left the factory fuel lines on the truck. The supply and return from the tank and the supply and return from the motor that “would” go to the hfcm are still installed just not attached to anything cause I have the fass now. I filled my truck up with fuel today and shortly after I did that, one of the lines coming from the tank whether it be the supply or return start leaking fuel bad. It appeared to be like filling the truck created a negative pressure in the tank or a siphon type situation. None of the factory lines are plugged off and I have never had a problem until today. The fass uses a sump and its own lines from that to regulated return on the motor. Just curious if anyone else has had this happen or something similar. I will be ordering 3/8” and 5/16” beans fuel line quick-disconnect plugs to plug the factory lines coming from the tank to hopefully prevent this from happening in the future unless anyone has other input or ideas on something I may have done wrong. Thank you for any help! So long for the short post!