I got two log files and both show "ASSERT!! MotionVector.c Line 133" a search indicates that MotionVector is from the original firmware
In case of a crash, the camera tries to record debugging information (function of the original firmware). When you request a romlog, you always get the information about the latest recorded crash event (watch the timestamp to see whether a new crash has happened).
In some cases the camera's operating system fails to catch the event and the crash doesn't leave a trace.
and the times stamps don't match the times when the camera actually stopped.
Are you sure? Your current log shows a fresh timestamp with about 78 minutes uptime (the 8 digit numbers in the second half of the log show the elapsed milliseconds).
If your camera crashes again, try to get another romlog.