Sounds like maybe you're referring to Beyond Burger, not Impossible Burger? Impossible Burger isn't available in grocery stores yet, and Beyond has sort of a spammy taste to it that Impossible doesn't have (from my perception).
Impossible Burger has been available in stores in the SF Bay Area for what seems like a few weeks now, if not longer. I remember it because it's expensive compared to real meat. I got it at Safeway. It wasn't the Beyond Burger.
That's fantastic if so. Their FAQ still says it's "coming later this year, find it at a restaurant". I follow them pretty closely and haven't seen any press about it.
FWIW, I have never seen an Impossible Burger in any Safeway (or Whole Foods) in the Bay Area. And I somehow doubt they would have just stealth launched an enormous chain without someone noticing; https://www.sfgate.com/food/article/Safeway-to-Carry-the-Pla... there are plenty of articles like this about the Beyond Burger getting into different chains.
I remember it due to the price. It was $8.99 for two Impossible burger patties. It's only $5.99 for two Beyond burger patties. It took me a month to get past the $8.99 price point for just two veggie patties. You might be able to find it at the same price point at Whole Foods as well. On that note, Impossible did mention that they were rolling out to supermarkets in 2019.
