Valor of the Ancients Buff - have I found a bug or a stealth change by Blizzard?

[concordantnexus]

I've been laid back about levelling and grinding, so I only first got the Valor of the Ancients Buff last week.

It survived the Tuesday reset.

My guilides insist that this was supposed to happen - have I found a bug or a stealth (undocumented in the Patch/hotfiex) notes change by Blizzard?