Hi Devil Dog,
What you see here is the same thing that's being discussed in this
thread.
Even though you may have never parked this domain through Sedo, since the domain is listed in your Sedo account, you're receiving revenue due to expiring traffic (may have been parked by another Sedo member using URL forwarding, eg:
http://sedoparking.com/domain.com).
Search engines like Google or Yahoo may have picked up the URL forwarded domain and others may have subsequently clicked on the URL forwarded domain => parking statistics for a domain that you've never parked at Sedo!
This isn't something that happens often, but we have seen it in a few cases recently and it's nothing to be too concerned about.
I hope this clarifies.
Thanks,
Monica