Since yesterday I always get this message when I log in via SSH:

2 packages can be updated.
0 updates are security updates.

There's nothing to be updated running apt-get update and apt-get upgrade:

sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.

(1 not upgraded: I can't find it)

I've followed these posts but to no avail:

Ubuntu tells me I have packages to upgrade when I don't

ubuntu server: SSH banner telling to update packages but nothing to update

Any hints/suggestions?
Thanks in advance.