Do you have or have you heard of any plans for further observation of UPS902 ?
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.