pink lines in my part - what are they?

Attach your pictures here not in a external link, most people will not open external links....

The first place that I would check is here:

And go through the highlighted list and see if there is a matching color.

could it be a center line?

hmm,.. since you are selecting a cut-sweep,.. normally, the pink would be the path  (the blue the profile).

I just had this same issue while working through the speaker surfacing tutorial. https://www.solidsmack.com/wp-content/uploads/2010/11/Complex-Surfacing-Speaker.zip  

The pink line showed up after the first boundary surface and would not go away.  I had turned on curvature combs while creating the feature. After I saw the pink line and went back to edit the feature I noticed the pink line was exactly where one of the curvature combs were.  I turned off curvature combs in the boundary surface feature and after rebuilding it was gone.  I tried to repeat it to get screen shots but the pink line doesn't come back now, neither with nor without curvature combs turned on.  I guess it was a glitch. Not sure if this applies to Erik's situation, but maybe helpful to someone else wondering what the weird pink line is.