Takao may notice that by now, the tanuki ears are lying flat against Midorima's head in annoyance. They're somewhat reactive, so it's a little easier to tell Midorima's emotions than it might be otherwise. At least 8 days out of the month it is, with a couple of exceptions where he's ended up with cat features (much to his annoyance).

"Typically within a month of arrival, each person finds themselves reactive to a specific moon. That's what they call a 'moonblessing.' Mine is Cordis moon, so don't get too close or you're going to have problems."

Takao hasn't even gone for a full space invasion yet, but Midorima's certainly noticed. Midorima typically has pretty strong pheromones, so being indoors or in close proximity to him can cause problems for some people. It's obvious to him that Takao didn't really pay attention when he was getting processed by the Lunatians (Midorima can't really blame him, it's hard to focus when you've been kidnapped to another planet and lost in the wilderness for a while), but whether or not he heeds his warning because of it or gets a face full of pheromones is on Takao now.