Final Prove for the G. Purity Fist Exploit Maybe...

From official steam TF2 Wiki there is a undocumented update applied that make me feel this way:

November 16, 2011 Patch

• Fixed an exploit that allowed untradable items to be traded with Steam trading.

November 23, 2011 Patch

• Made the Cold War Luchador, Mark of the Saint, and Apoco-Fists tradable
• [Undocumented] Fixed a Steam Trading bug that allowed items to be duplicated.

Source:

http://wiki.teamfortress.com/wiki/Trading#Temporary

So, as you see it very likely what happened to that incident make steam apply this bug fix.

Now G.Purity Fist price will lower to 1ref~2 ref for either G or normal.

Thank You