I've got a very old dhcp server which is behaving weirdly.

In the dhcp.leases file I see loads of the following:
lease {
        starts 2 2006/09/19 15:31:36;
        ends 2 2038/01/19 03:14:07;
        client-hostname "somename";
but the lease time is set for 1 hour in dhcpd.conf (always has been) and this is verified by the fact that other leases in the same dhcpd.leases file show
lease {
        starts 4 2006/09/21 08:33:51;
        ends 4 2006/09/21 09:33:51;
        client-hostname "someothername";
Does anybody understand this? Is this a known problem or something?

I have manually deleted all the abandoned leases from dhcpd.leases before but they do reappear over time.

Why is it giving out leases till 2038??!

(server is dhcpd-2.0b1pl0-1 on Red Hat Linux release 6.1 - Yes you don't have to tell me, I will replace this)