Routers along the way can take different paths on the way back, and I think this is what is happening here. The problem is more easily seen doing a reverse trace. This router shows over 2 seconds of latency, and affects all routers beyond it back to me. Notice hop 7 is a different IP address. I've got a ticket number.
All agents are busy - leave a message' on their phone line.
I leave messages, but they don't call back. I call that number. There's no option that fits my situation, but I try their tech support anyway. They even create a ticket number, and send an automated response to me. I'm told that I'm not a UUNet customer, and they can't help me - Roadrunner needs to contact them.