sudo never asks me for a password

[Kamil Kisiel]

For some reason, on this particular FreeBSD machine, sudo never asks
me for a password, even if I haven't logged in for days. I tried
running sudo -k, sudo -K before trying it. I've even tried manually
removing /var/run/sudo.

When I run sudo -l, I get:

User kamil may run the following commands on this host:
    (ALL) ALL

The contents of my /usr/local/etc/sudoers file is:
Defaults authenticate
root    ALL=(ALL) ALL
%sysops         ALL=(ALL) ALL

I've been struggling with this problem for some time but still haven't
been able to find a solution. Any ideas?

-- 
Kamil