Why doesn't new linux kernel appear from security two days after release?

[francis picabia <fpicabia@gmail.com>]

When I do apt-get update && apt-get upgrade to get

the new kernel which is part of DSA-4308-1 (released Oct 1),

I get nothing available.

I have in sources.list:

deb http://mirror.csclub.uwaterloo.ca/debian/ stretch main contrib non-free
deb-src http://mirror.csclub.uwaterloo.ca/debian/ stretch main contrib non-free

deb http://security.debian.org/debian-security stretch/updates main contrib non-free
deb-src http://security.debian.org/debian-security stretch/updates main contrib non-free

I've tried apt-get clean and even apt-get dist-upgrade

Nothing makes any difference and no packages are reporting held back.

System has been running fine for several months.  Another system with the same

sources.list was recently rebooted with the updated kernel.  Both are on

unattended upgrades, so I was surprised the one system isn't getting the update.

I can install new packages fine.

Are there steps I can use to debug this issue or force it to really see what is available?

mtr shows I can get to the host alias security.debian.org