ebay dropping asymmetric traffic?

Ever notice you can't reach routing peeps by phone anymore? I have a few networks which are routing out one provider and return another. Not general practice, but it's ended up that way. As of last night I've had reports flowing in of these networks unable to hit ebay. The other networks in that area which leave and return via the same route seem to be working, and the broken networks returned to operation status when we forced ebay traffic around the network to make the flows symmetrical. I've heard this is causing problems in other networks as well. Has anyone seen this? Any idea of the specifics? I'm almost tempted to believe it's some form of RPF on inbound traffic (the observed path was via their cox interconnect). Jack