[Vimpulse] Strnge behavior in Info (and probably other modes)

When I M-x info, I get the full viper bindings. However, after a random amount of time, or maybe after I do some other stuff (like running gnus on another frame it seems) the nice vimpulse bindings get loaded. I don't really get what's going on, and I don't really know what do I do to trigger the loading. This time it was gnus, but I think other times it has been something else, maybe org-agenda. Do you have any idea what's going on? __ Alessandro