Received the following reply from PayPal Global Technical Support regarding my inquiry about this problem:
"Our Engineers are currently working on temporary measures to address the issue. The problem is twofold between eJunkie, and PayPal related to the way our Integration has changed over time and eJunkie not adapting to those changes as intended. I believe the plan is to roll back some of those changes, but I am still wanting on a confirmation on that situation."
As I read it, this blames e-Junkie.
My response so far has been to no longer use PayPal with the e-Junkie cart.