Uh, I didn't lose anything, but I'm highly confused about this transaction: http://puu.sh/27MuV
As you can see, 2 scraps went out of my shop(which never existed there) to someone else for nothing in return.

I'm kinda confused, what's the meaning of this?

I added the guy that shows up as the 'partner' of your trade. He told me that he tried to buy one of your strange part but did not complete the trade. At the nearly same time, someone was withdrawing 2 scraps from Dispenser 71, and this mysterious log appears.
But actually, nothing went wrong except the log so it does no harm. We will take a look at the problem when we have finish what's more important right now.