For some reason my N function showed up in red even though I haven't noticed it in that color before. The color actually makes the code much more readable but I just don't know if I should be alarmed or not.
I applied a different stylesheet to my notebook (as you can tell by the color of the input I've been modding my own stylesheet) but the color is still there. I also checked on the Appearance tab of Edit > Preference and the only red syntax are the errors. I doubt "N" falls into any of these and I also can't tell which shade of red it is to match it to.
Update: this is getting weirder:
After restarting MMA, the N is no longer red :'( Also, I can't seem to File > Save Selection As without setting the window size to 100%. If the size is not 100%, I got the error that "The specified setting for the option WindowSize cannot be used."
This was reported to be a bug so I suspect my red "N" is also a bug (because previously, with the red N, I could save my selections at sizes that were not 100%). It was nice while it lasted I guess, though I really hope WRI adds better syntax highlighting in their future releases.