What does CP do with the coasters that the trains roll back on cold morning?

I think I read that on that website "Tour The Point"

Didn't the blue train on Gemini roll have a roll back going up the first hill after the drop earlier in the season that just passed?

I technically know how to cause Mean Streak to roll back.

The brakes near the top of the first drop might cause a rollback if they are on as an empty train passes.

cyberdman said:
I think the more appropriate correct term to be using here is 'valleying'. Mean Streak has done this many times as well as Gemini.

Valleying or Valleyed doesn't make sense. Roll back in terms of a roller coaster means that the train failed to proceed forward past an element causing the train to roll backwards. Even rollback as one word has the same meaning. Adding an -ing or -ed to the end of the word valley doesn't change it's meaning.