There are some things I've never properly established for my cast - I don't have their blood types or their birthdays or a list of everyone's favourite foods. This is for two reasons: on one hand, it's far too much work for something that doesn't matter to the story, and on the other hand, leaving it unstated allows me to insert something specific later if a plotline requires it.
One of the things I could specify but haven't is all the cisfemale characters' menstrual cycles. Leftover Soup does have a specific timeline - if I wanted to, I could easily make a little day chart and line up everyone's uterine schedules on it. "Okay, this is the third week, so in this scene, Gina is just starting her period and Nicole is just ending, I'd better be sure to let that information inform their mood and dialogue in this conversation about fourth edition D&D rules..."
I'm not going to do that - not for my work, nor for any other work of fiction. It would be creepy as fuck.
As I've stated before, creepiness is in the eye of the beholder. Jamie's specific behaviour here is only creepy insofar as Ellen had not expected it. Certainly he hadn't intended to be unnerving or inappropriate. He just happens to be observant about the wrong things - as Ellen said: low Wis, but points in Spot.