No it is not. I am getting it too. It's a bit odd.
So I have enabled something today that might give me more insight next time it happens, except of course, it hasn't happened since lol.
It's an odd one for sure, and something I have not seen before in my career... (In that the server does not show any errors, the logs show that it sent the page, yet the browser shows nothing. NOTHING... *huh*.. )