The striding, what with knowing next to nothing of Mel other than that she's annoying and walks into situations blindly, is really kind of irritating to Rachel.

When her posture straightens, Rachel's pace actually does slow, just slightly. Enough so to look around.

She does not need to keep up just because Mel is blindly plowing forward. She does not.

But it's odd to see the tunnels change before they've even found a symbol. Surely that part of the Labyrinth wasn't flexible?