[tex-live] a question about when gets the TL database refreshed in mirrors

[jfbu]

Hi everybody

I have noticed that my local mirror (e.g. ftp.oleane.net)
has more recent versions of some packages than are installed
on my computer

However when I ask TeX Live Utility or the command line tlmgr
to check for updates, either without specifying a mirror, or
when specifying this specific one, it tells me there are NO updates
available

if I understand correctly there is a texlive.tlpdb file on these
mirrors, so my question is when gets this file updated? 

the delay in synchronization is 24h? or one week?

(I saw announced of updates in packages on the RSS feed quite a few days ago,
and I now checked that indeed the CTAN mirror typically accessed by my
machine does have these updates)

thanks for any info about what to expect,
PS: it is perhaps a problem with the files on my computer

regards,

Jean-Francois