I believe if UPS902 continues its current daily flight time +/- 20 minutes for variations in the arrival (wx, winds, delays at PNHL) the window of observation for a smliar contrail decrease on a daily basis as the sun sets a few minutes earlier each day. Throw in the variability of weather conditions at cruising altitude, and the ground (for observation) and I think it would be prett difficult to observe the same effect. Not out of the question, but more difficult as the days go by.
So, to answer your question: no, I personally do not plan to make further observations of that particular flight. However, I do plane to make future observations in the Seattle area of incoming flights around sunset that match this flight path. We get daily overflights by Fedex MD-11 or 777F flights from Japan to memphis that often occur around sunset, again depending on many conditions. The downer is getting a clear horizon in Seattle in November.
You can use AWE808. It arrives 30 minutes ahead of UPS902. And just like UPS902 it stays at cruising altitude > 29,000 feet while over the ocean. On the day of November 8th AWE808 was already over Catalina Island 14 minutes before the event was spotted 35 miles SW of LA. So we are absolutely certain that is was not AWE808. 100 %. It actually crossed over California mainland at 17:06:00 on that day. Well before the event. BTW - it took 4 1/2 minutes to get from Catalina Island to the California mainland in OC.