YuriPander 2
That said, this screen is one of the reasons why I find this show just disappointing. There's absolutely no reason why they need to keep it a secret other than it's a conceit of the show. There's no fear of the outside world intruding onto them, or of homophobic parents/friends/peers judging them. They just have to keep it secret just "because".
Probably one of the weird things is that while yuri is probably read in equal numbers by men and women, in terms of disc sales, they are probably depending entirely on men. So I don't know if they just need to amp up the perv factor in order to make this work by having the girls kiss in every single episode or what.
I will say, having read the 4koma again, that at least the anime is providing a fairly functional adaptation of material that is rather dry. It's weird that, as someone who wouldn't mind seeing more yuri anime, I would almost like this show more if the girls were just straight/pseudo-yuri and it was just like any other four (or six, I guess) girl anime.