The two kids had been to a Chuck E. Cheese restaurant at one point during one of Holly's birthday parties, and to be fair, Evan didn't exactly enjoy himself.

For one, the high abundance of lights and sounds, alongside the amount of people, were pretty overstimulating for poor Evan due to his autism, so he and Holly tended to step away from the crowds and take some time outside to help him calm down.

That, and considering how the animatronics and mascot costumes tended to scare children back in the day, Evan himself was pretty much terrified by them. Holly was quite unnerved, too, though would stick by Evan's side to reassure him that he's okay.

So naturally, they're both tense from that past experience, and if they ever encountered Chuck E.'s animated counterpart from the adverts during their adventure in the childhood worlds, you can guarantee they'd both be pretty on edge from it and wouldn't trust the mouse mascot immediately.