A local store in Denver was selling Kodak paper that way after Kodak got out of the paper biz. Seems that there weren't problems. I have had corner fogging myself, however, due to rips in the interior bag.
I accidentally opened a bag with the enlarger left on last week and, though only on the edges, there were some density marks along the edges due to exposure to the light from the enlarger so I would count on at least some exposure on at least some of the paper. Hard to say how extensive. You might test one sheet and if you can tell what portions of the paper might be affected you could always print around those areas and hope that it doesn't change form sheet to sheet.
Thanks for all the responses guys.
The bag was not open. it was folded under the mass of paper yielding it "closed"
I store my working stash of 8x10 in the darkroom in the naked black bag. The only thing holding it closed is the flap folded over and the weight of the paper holding it shut. It sits on the shelf; I leave it out and exposed to white light like that. I haven't had any trouble at all doing this.