u.arin.net - slow to update ?

I don’t mean this as a complaint. Looks like this NS is ran out of PCH. I made some changes to a zone via ARIN (within ip6.arpa) and it seems like all auth servers listed one level up picked it up within an hour (possibly quicker) - however u.arin.net is still in the dark. Is this a known issue ? I can wait 24 hours - not a biggie… Thanks.