Control key function reversal?

In the middle of a modeling session, some combination of fumble-fingered hot key use managed to reverse the function of the control key for controlling moves or extrudes - that is, without the control key held down, I could only extrude in 1 blender unit increments, but if I held the control key down, extrude worked as expected - this is opposite of the way it’s supposed to work.

I spent half an hour searching the documentation (2.66a by the way), and couldn’t find a solution.

Finally started a new drawing, appended all my objects from the one in progress, and the problem was gone.

So, is this a bug or a feature? Just in case I manage to reverse the control key operation again by accident, is there a fix?

thanks!

thanks a bunch - I appreciate the help!