I’ve had this issue too, while implementing BOSH:
(returned by Openfire.)
After checking Openfire logs I saw something like:
rid 123456 > 123455.
It turned out, that I’ve sent a with a an unexpected rid, e.g. Openfire expected 123455, but I’ve sent 123456 instead (before sending 123455).
In your logs in the mailing list, you sent:
2962056780 (I suspect this to be the problem).
Although I believe according to the spec, an XMPP Connection Manager should just return a cached element for cases, when an ack was not received and the client tries to resend an old message (with old rid).