Browning/discoloration of sets in boxes??

I recently picked up a complete set of 1984 Donruss from an eBay auction. Got it at a really good price and it was from a West Coast dealer with great feedback.
Got the set today and it was in a standard white card box. The second I opened it, I noticed the top edges of cards were brownish, more than I thought was normal. The first card is the Robin Yount Diamond King and the back of the card was facing out. It was very brown and the next card's back was completely white. All of the browning is on both edges of the set. Otherwise, the conditions of the cards were very good and there was little discoloration outside the edges.
The cards and box don't smell like smoke or mold at all. Curious as to how common this is for white edged sets or other opinions. I don't have a lot of experience with this.
Thanks
Got the set today and it was in a standard white card box. The second I opened it, I noticed the top edges of cards were brownish, more than I thought was normal. The first card is the Robin Yount Diamond King and the back of the card was facing out. It was very brown and the next card's back was completely white. All of the browning is on both edges of the set. Otherwise, the conditions of the cards were very good and there was little discoloration outside the edges.
The cards and box don't smell like smoke or mold at all. Curious as to how common this is for white edged sets or other opinions. I don't have a lot of experience with this.
Thanks
Currently collecting PSA graded:
1991 & 1992 Fleer Pro Visions
1952 Topps
1991 & 1992 Fleer Pro Visions
1952 Topps
0
Comments
Due to the strong stench of cigarette smoke (mom smokes), I had assumed that the staining and the smell were related. The lack of a smell from you cards could mean that they were sufficiently aired out and re-boxed, or that the staining is caused by something else.
WTB: 2001 Leaf Rookies & Stars Longevity: Ryan Jensen #/25
1991 & 1992 Fleer Pro Visions
1952 Topps
recently. They had been there for about 10 years. The edges of the white stock had turned brownish.