I was so happy to buy 'Just Mayo' at Costco but it doesn't appear to be there anymore.
This is from an article on VegNews from August of last year, and might answer your question, or at least give you a place to start looking for answers:
On Friday, retailer Target informed Hampton Creek—makers of popular vegan condiment Just Mayo—that it would end its contract with the food technology company. On June 22, Target inexplicably removed all of the company’s 20 products from retail and online outlets after receiving a fraudulent letter that claimed, among other falsehoods, that Hampton Creek products could be contaminated with listeria and/or salmonella. At least one other retailer of Hampton Creek products received a similar letter, and, instead of removing products from shelves, contacted Hampton Creek directly to settle the issue. Last week, Hampton Creek announced that the Food and Drug Administration (FDA) had cleared the company’s products of any potential health threats and revealed that its retail team had begun negotiations to be reinstated at Target. “To our surprise, Target informed us that sharing with the public the FDA’s conclusion that our products are safe somehow violated Target’s vendor communication guidelines,” Hampton Creek CEO Josh Tetrick said in a statement, wherein he also mentioned that the company’s vegan cookie dough was the best-seller (outselling similiarly positioned brands that contain animal products) at one major retailer prior to Target pulling its products. Tetrick told VegNews that the company will not pursue further action to reinstate its products at Target and that Hampton Creek will move forward in its pursuit to replace animal agriculture with plant-based foods, adding that the loss of Target’s distribution points will not pose a substantial financial threat to the company.