Thanks for all your input yesterday regarding the zipper. I took my Ribby Cardi to my knitting group and got some expert advice. The consensus was "Do Over"
I'm really not happy with the zipper showing. I know it's only a matter of a few millimeters, but it bothers me.
To clinch the deal, I looked at a favorite commercially made zippered cardigan I have and looked closely at the zipper. Look! Not a sign of the zipper showing on this cardigan.
That really helped me make up my mind. I'd rather rip out the zipper which I had only basted in place and start over. It will take me another day of work, but in the long run, I know I'll be much happier for it.
I also weighed everyone's input - both online, on Ravelry, and amongst my knitting group friends and have decided that I will hand sew the zipper in place.
So that's where I stand. As you're reading this, please know that I'm up to my elbows in pinning and basting this zipper. I have faith that it will turn out perfectly!