I think it's just a matter of them trying new products. Maybe the vendor sold them on it. I've learned over the years that if I find something I really like only at Wal-Mart I better buy as much of it as I can use because they'll drop or change the product in a year or two. That's just how they are - always trying to cut costs.

If you're really interested in Wal-Mart, the 'pickle' and 'lawnmower' stories are interesting reads:

http://www.fastcompany.com/magazine/77/walmart.html
http://www.fastcompany.com/magazine/102/open_snapper.html