Signs posted in the restaurant thank their patrons and say that the owners are seeking a new location to reopen the business. Sunday, April 28th is apparently the last day to get a bowl of hearty soup at the current location.
A new Vietnamese restaurant, Lan Chi's, opened in the neighborhood recently, but that doesn't seem likely to have played a role. As multiple online reviews attest, Pho Mai built a loyal following offering good food for an affordable price in a friendly, no-frills ambiance. (Scuttlebutt is that a bank is taking over the building where Pho currently rents and wants it tenant-free for some reason... but that's just hearsay.)
Meanwhile, if you want to get a last (or first) taste of one the city's fine restaurants, you have a few days. Cash only - they don't take credit cards.