Pubsubhubbub stops working after feed node update

After the initial creation of the feed, the PSHB subscription works as expected.

But every time i edit and save the feed node, I get the "Could not verify subscription." log message.
And i notice that the secret phrase changes every time i save the node.
Maybe the hub is still using the old secret phrase which doesn't match the newly-generated one so the verification always fails.

Here're the two messages i get every time i save a feed node.

Type	FeedsHTTPFetcher
User	Anonymous (not verified)
Location	http://.../feeds/importer/1?hub.verify_token=......
Message	importer:1 Could not verify subscription.
Severity	error

Type	FeedsHTTPFetcher
User	admin
Location	http://.../node/1/edit?destination=admin/content/node
Referrer	http://.../node/1/edit?destination=admin/content/node
Message	importer:1 Positive response to "subscribe" request (204).
Severity	notice
Hostname	local ip here