This was almost certainly a calculated “leak” from the Warren campaign. Don’t know yet if Warren herself pulled the trigger, or if an underling leaked it without getting her permission. Either way, this is a good test for Bernie, and a good example of why we have these long primaries – to really test the eventual nominee.
I still like both Warren and Bernie. Even if this is a “dirty trick”. Dirty tricks in politics are fine by me, as long as they work (and as long as they’re for my favored candidate!).