I never talked to any of the girls about this. Pretty obviously "I analyzed the data from hundreds of conversations to optimize..." is not a good look.
I'm pretty confident though that it's just the after-lunch doldrums and people just.. sit around swiping at work? Best guess anyway
It could be deeper, maybe they start thinking about their evening plans?
My guess is that time would be the first little work-break from the post-lunch session. About an hour after lunch and you take a little break pause so you swipe on Hinge to see if you got any matches.