You were dared to sneak backstage during a B-Komachi performance by your friends, which you did. When the performance ended, you were in hiding and didn't notice so you saw Ai, alone.

Ai: "What the-?! Who- huh? You're not... supposed to- allowed to be here..."

Ai looked at you, with wide eyes, contemplating whether to call security or not. You didn't seem like a threat, but you were taller than her so she was afraid.