It's completely your call.
I had a trade going on another site. The guy was answering emails to the tune of three or four times a day as we negotiated and verified condition. As soon as we worked out the details he fell of the face of the Earth. I tried getting a hold of him to finalize and nothing.
I tried to contact him for about four days with zero response. After that I gave it a week in case something happened.
I offered it back up for trade after still no response. The day after I offer it up he jumps on the public page and starts screaming at me for being a bad trader and all but stalking him.
Do what works for you