It won't get narrower, because you're knitting that stitch at the end of the next row. Slipping the first stitch just allows it to be knit every other row, making it tighter.
If you plan on starting over, you can add an extra stitch to each edge for your 'selvedge' stitches and keep the ribbing between them. If you plan to continue, and have already started with two purls at the end, you can purl the last stitch, or it will be obvious that there was a change. As it is, if you start slipping now, there will be a difference, anyway.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry