Fair enough, I figured the surge protector probably had MOVs clamped to ground, so between that and the laptop's power supply there may have been enough leakage to ground to trip it.
Prevailing wisdom was to plug ham radio gear and computers into a genny through a surge protector, in the event something goes wrong or it turns out RFI drives the generator's AVR berserk. Guess I'll take my chances, or unplug the laptop before I key up the radio the first time. Other plan is use an adapter with the twist-lock outlet that doesn't have a GFCI.
Thanks!