More of a gee whiz kind of question than anything of import.

I picked up a 3 day GS today. It is a 4 day trip that started yesterday as captain OE, and I'm picking it up at the end of day 2 through day 4 when I presume his OE will be complete. When scheduling put it on my line, they put the entire 4 day on my line. I only expected to be paid 3 days and that is what is on my time card, so any idea why they put the 4 day trip on my line when from my perspective it's really only a 3 day trip?