This is the very thing that I was complaining about.
Ahh! Now I got you. Yes, that's a bug (SMACK-643) in 4.0, which doesn't exits (or shouldn't) in 4.1. Since we have a release candidate for 4.1, I recommend updating to 4.1. But please refer to the https://github.com/igniterealtime/Smack/wiki/Smack-4.1-Readme-and-Upgrade-Guide and note that the list of API changes is incomplate (feel free to add any items you may discover).
I've just uploaded Smack 4.0.7-SNAPSHOT, which should fix the problem. Would you be so helpful and try this version, reporting back if it fixes the issue or not?