Nothing you do in PrPro or Speedgrade changes the original footage other than creating full subclips makes those clips as physically separate copies of those sections of the larger footage file. So no, you haven't done anything whatever to your footage. So as Dmitry suggests, you've managed to stumble into a keyboard shortcut incidentally that did something to what your display is showing. Any display of individual color channel of course "appears" as a gray-scale view. So, it's either showing a gray-scale view of the combined OR a gray-scale view of a single channel. You can look through the menu options on the monitor panel probably or the controls panel and figure out where the problem child is ... good luck and good hunting!
Neil
