Well, I've apparently pulled a Mark Leuck, and cracked the frame on the Rocket... it's on the bottom, behind the idler hanger.  Just happened to notice it when I had turned the bike over to work on the rear disc brake.  I contacted Jerrell, and he said they have had two Rifles with the same issue, but this is the first Rocket.  It's a natural high-tension-stress location, when the back wheel takes a jolt.
 

 
They have already changed the bike frame design to eliminate the welded-on idler hanger, eliminating the tube discontinuity and heatstress-related fracture point.  They've gone to a clamp-on style idler, and he assures me it can take the power-side vertical force and not rotate.
 

 
Interesting "polished metal" look to that frame, eh?  I'm investigating further.....  
 
Paul

Oooooo!  Aaaaaah!  shiny object!!! .  Màn on a sunny day that thing might be a danger to fellow riders
 
 
Sorry to hear about the crack.  

Talked to Jerrell yesterday...  the couple of cracked frames they've had are all "XL" length, which would be more susceptible to the issue than a shorter frame -- both from being a longer "truss" and probably having larger, heavier riders.
 
When they first discovered it, he immediately did some load testing to failure -- and found that the location tended to fail at about 850 pounds.  He then tested a frame with no weld or discontinuity at that point, and went to 1000 pounds without even bending the frame.
 
So, they have since gone to the T-Cycle idler shown in the photo, eliminating the welded idler bracket.  T-Cycle has tested the idler on trikes with a much more severe chain angle and torque, with no problems.
 
The "polished bare metal" look is what he is going to send me on the replacement frame.  Not sure when they'll "officially" offer it, but he says its very promising so far.  I should have it in about 3-4 weeks.