To understand what's going on with WalMart, you have to go back several quarters. Awhile back, WalMart implemented a (failed) strategy to dramatically reduce the number of SKUs on their shelves to lower their operating costs. B&G took a hit when that happened, as several of their products were removed from shelves.
Later on, Walmart realized that the strategy was cannibalizing overall sales so they announced they would reverse course. This double-digit sales growth to WalMart is probably just a short-term blip to re-fill inventory of some of the products they've decided to put back on the shelves.