Pokemon white 2, is this supposed to happen?

Question

Umm so I went into reversal mountain and walked around with Bianca following me. As soon as I got out to the south exit, I recognized that I needed some things from the Pokemart as well as something from my PC box. So I walked back to the beginning and proceeded to leave but decided to be lazy and used an escape rope. And apparently it brought me back to the south exit/opening that didn’t leave the mountain.
After I went back in, bianca’s Dialogue appeared on my screen so I though Bianca was trying to yell halfway across the cave..? When I was going back to where I left her, she came back with red demon eyes.
Is that supposed to happen or what.(my game didn’t crash.)

Answer 1

That is a glitch that happens in B2W2.

Phantom Bianca glitch

When going through Reversal Mountain for the first time, if the player enters the dungeon from the left side, causing Bianca to follow them, then goes through the southernmost exit and comes back inside, returning to the start of the cave, but not leaving the mountain entirely, Bianca will ask to split up. The player will then move to the next screen, where if they then use either an Escape Rope or Dig they will exit back to the southernmost point. Returning to the main part of the cave will cause Bianca's dialogue box to appear, but for her to be out of sight. After walking around for a while, she will eventually catch up, but may travel through walls in the process.

Scource