I read on German users Mailing List
<http://listarchives.libreoffice.org/de/discuss/msg14616.html> that Libo Portable simply recommends update to the next more current Version. That's a very bad idea, users, who want to use a very stable version (3.6.5) definitively will not want to update to an "Early Adopters'" version. And many of those users will be overextended with rating whether the recommendation is appropriate.
We should find a way to synchronize the Portable Update recommendations with our ones, what respect the special needs of different users.
BTW, I am currently not able to reproduce the problem, my German 3.6.5 Portable told me "is up to date", when I checked for Updates.
Closing as WFM since we don't have confirmation that it works as stated (Rainer was unable to confirm)