Looking at the examples of the different style PSA "slips" through the years, this looks like the style 3. Man you guys have got me so concerned because I have a 1951 Bowman Mays in PSA 6 that has the exact same characteristics and my feet have been literally sweating since I started reading this thread. So much so that I contacted b-e-collectibles who I purchased the card from in December with my concern.

I also looked on ebay and there's one listed on ebay in PSA 6 that has the exact same style slip with rounded white corners, but the bar code is completely different than mine...so that makes me feel a little bit better.