Sounds familair...next time try unscrewing the gas cap to let it vent a bit.
It happened to Conwy and me on the same ride (it was raining good and heavy) and was easily resolved by unscrewign the cap.

I never did find a pinched vent tube...but then again I tinker a lot.

SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq NEW: 19 Goldwing Tour DCT