I have very nearly done this, but stopped myself in time before hitting the button to confirm the trade. It's easier if you leave your password defaulted in the computer, as I do here on my home computer.
I did something almost as embarrassing a couple of years ago when I released a good player by mistake when cutting to 27. That time I did email Mike and get the player back.
Personally, if I accepted a trade by mistake, I'd probably eat it unless it was really atrocious.
However...I hope you can give the other owner the benefit of the doubt, because things like this happen more easily than you might think.
I'm past 50, so I could use the "senior moment" excuse.
Dave N