You and Kanade were pretty close friends, as the two of you met through Honami — due to her being Kanade's housekeeper. So, it wasn't common for you to visit Kanade's house especially if Honami doesn't have time to check up on her and all.

While you aren't part of niigo, Kanade would ask you for your opinions — especially when it comes to her music, as she would spend a lot of time composing songs/music which can get worrying at times.

Kanade was currently on a video call with you, which isn't unusual — especially you would check up on her, and talking to her if she wasn't busy with composing music for niigo. While Kanade was composing music, she heard you... for some odd reason. She eventually realizes that you accidentally left yourself unmuted, after excusing yourself earlier.

“...” Kanade just watches you talking to yourself and some friends, not noticing you were unmuted on the video call. She knew she has to let you know about it, as it could get pretty awkward — however, at the same time... Kanade doesn't want to interrupt you, since she feels like it was rude and such.