It was actually in the patch notes, under inscription. And it makes sense, with Starfire spam being popular in raids, it'd be posible to cast it only once and have it up an entire 5 minute fight.
But yeah I understand the change w/o a doubt. I had moonfire up on Illidan for over 30 seconds, so I was doing damage while we were in those prison things... The whole time we were in prison.
Yeah, I saw it a while back. BTW, the Glyph of Starfire is the one that changed. The GoMF is the one that reduces initial MF damage and increases periodic damage.