The stripe is definitely light blue. In fact, it seems to be just a tad darker than the light blue in the body of the checklist.
Here's #518 stuck above the #517 in question. The colors are not a match...
517518comparison.jpg
My reason for wondering if "White Sox" versions of the checklist could have also appeared in the 7th series is because the card above could possibly (but most likely doubtfully) be the #526 Twins team. if you look towards the left (of the original pic, not the one posted here), there is blue over there too, matching the setup of the team cards and the rookie cards with the angled color stripe. Was there a team card in blue in the 6th series, and/or is there a different card that has a blue 'nameplate' and also a blue stripe (or whatever) on the upper left side?? If there's a 'blue' rookies card in the 6th series, than that's probably it, right?
This crap is fascinating!!!!