I like to gamble with Runes in the Mystic Forge, as I salvage every piece of gear I get, but had this happen for the first time to me that I can recall.
I placed 4 not account bound Runes into the Forge, and got a Major Rune of the Monk back. Well first I was happy it was an upgrade but realized its Account bound. So all I ask is this
Remove Account Bound status items from the Mystic Forge loot table on Runes, unless an account bound item is placed into it.