As the title says. In the middle of a dungeon I discovered I was using a random junk-loot lightning staff instead of my treasure hunter flame staff. How did I do that I wondered? I re-equipped the flame staff and continued.
Then I just logged in right now and found that three random armor pieces had equipped themselves in place of my treasure hunter and {mismatched of course - I am a magic user after all) monster helm. See the attached screen shot.
TL:DR - random armor/weapons equip themselves on my character on their own. All since this new update.