Hi. This is very similar to

 http://debbugs.gnu.org/cgi/bugreport.cgi?bug=19669

but with different input.

I'm running an emacs built from 65ac8bc (master branch as of 2015/4/18)

Recipe:

1. emacs -nw -Q tst.c (open attached source)
2. C-n C-o //         (navigate to next line, start a new comment)

At this point, the buffer looks like the attached image. Note that at
step 2, the coloration of the 3rd and 5th arguments changed. This is
wrong. In normal use I see this popping up in response to various
inputs, not just starting a comment in some arbitrary place.

Thanks