I'm able to get good reception at home and we finally have a little wx that is showing up in the weather mode. The GMT time appears correct at the top of the circle. The time went from -35 min to -25 min when it updated (I just happened to be watching it).
Maybe -25 min is as good as it gets?
Bill
Update: Just checked and last update was -7 min!
Update 2: An hour later - new wx is displayed with a very small circle. The Z time is obscurred by the green circle of an airplort. Age of NEXRAD shows -1360 min.