FYI to others:
As Ray explained, without being able to reproduce error, impossible to troubleshoot. I've told client this over and over to no avail. Client just says "customer had this issue" but no way to know what exactly happened.
I posted to see if there was anything that sounded familiar to WA that could hunt down the problem. Nothing similar, so a specific case. The customer of the client could have lost his connection for all we know.