Switching MY session's "Environment > Daylight savings time" option from "Adjust remote timestamp to local conventions" to "Adjust remote timestamp with DST" seems to workaround the issue... at least, now I seem to match what the other machines are reporting.
I was running WinSCP 5.1.3 before but upgraded to 5.1.4 to see if the issue was solved. It didn't, same issue in both versions.
Any idea what's happening?
At first, I thought the Nginx server may have poor timestamp handling. Except my coworkers (who use the "Adjust remote timestamp to local conventions" setting) have no problems. And the only difference between me and my coworkers is the use of Windows XP.
I've attached the log files. For the record, we're in Pacific time (GMT-8:00).