Just tried rebooting, dif USB port, 0.9.10b8b, same error:
"One or more blobs rejected by the Cydia server.
Cydia server refused blobs pulled from this device."
Cydia does NOT have 5.0.1 blobs: I jailbroke AFTER the signing window.
So you should have the dumped blobs on your comp... on Mac they go into the same directory where the app was run I'm not sure where they go on Windows. Find the blobs and then use the verify feature and it'll tell you if it's a full set or not.
If you getting a message like Cydia rejected them you must have them locally.