Does the Fuji have TTL Metering? That tends to get rid of most of my lenscap shots, but even that is still not infallible.
Taking a shot indoors on Sunday, Bessa R3A and Nokton 40/1.4 wide open, TMax 400 and meter set to 800. It was dark indoors and the exposure-indicator was blinking '1' (meaning underexposure), but I clicked anyway. Only afterwards I thought "even that's too long" (I'd just been taking MF shots with Delta@3200 f/2.8 1/30s in a slightly better-lit room), so I checked and the lenscap was on...