How are they measuring that and what are the units?
There is an obvious contradiction in your statement. If it occurs when > 2.6, then why not occur if currently > 3? Since quakes release stress, 2.6 would be an upper limit.
Somewhat of an odd question. In your own linked UGS report , the figures show repeated large earthquakes at the junction between the Southern Mojave Fault and the San Andreus Fault each time stress exceeded 2.6 MPa.
Yes, current modeled stress is higher than 3.0. Earthquakes are random, and friction between miles of rocks is never exactly what it was the last earthquakes in the same spot. But, on average, yes. We are overdue.
Just like the Cascadia Fault offshore of the entire coast from BC-WASHINGTON-OREGON-NORCAL. We are overdue up there too.