@BugDemon
I'm using page 2 as comparison. Anri, Momo and Mikan were making pom-poms with Momo in a bad mood and going on about cats, then Shamiko joins and at Momo's next scene she is already industrious.
But yes, now that I think about it Momo does look like she is enjoying herself so just trying to showcase herself can't be it.
It could be that Shamiko's presence shifted the mood for Momo to give it a try and find it gratifying, or like you said, she was already invested but being tsundere about it. I still found the change a bit too quick and stark (though that can yet be rather for the comedy).
Edit: I fail too see the need for sarcasm, as nowhere am I implying Shamiko is all Momo thinks about (you make a strawman argument with that)