They have a mixed fleet?
PSEU- If it's an NG. non dispatch item.
Master caution would give a warning light, too.
ground crew pre push checks
I can't see this as being anything more than a door indicator. I'd doubt the authenticity of this comment-
Jeff Weingart was killing time at the airport when he saw it all unfold.
"I couldn't believe my eyes," he said. "I couldn't believe a plane as sophisticated as they are would take off with the cargo door open."