As far as I know, Vanguard only updates the ERs when they update the fund's prospectus, which happens on a yearly basis. And April 28, 2014's prospectus shows VTSAX with a 0.05% ER, so your memory is correct.
I've never actually seen a note inside my account informing me of an ER change, though I've never gone to look either. But I just checked my account, and I have a note for VFIAX showing an even crazier change: 0.09% to 0.05%. Like your case, I know VFIAX has been at 0.05% for a long time.
So I'm guessing it's just some kind of bug in their platform (though maybe that's what they want me to think!)
Every month they publish a "news" article showing funds with updated prospectuses, and which of those (if any) have had their ERs change. It doesn't appear yet that they've published the April 2015 version of this article; perhaps that will explain it.
Regarding 1984, my Google Maps Navigation just did this. I was driving somewhere and it sensibly had me on a route that used an expressway. Then, suddenly (and without explicitly informing me), it changed my route to use surface streets only. I thought "huh, a really bad accident must have just happened on the expressway and Google knows I should avoid it; that's the only way this surface-street route will be faster than the expressway". Then a few minutes later, she spoke up and said "new route found, it will save 10 minutes over the current route. Would you like to take it?" Oh Google, you're so smart, you've just saved me 10 minutes! What would I do without you?! (of course she had just flipped back to the original expressway route).
