weird time offset?

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

My xen domUs (i386, dom0 and domU both NetBSD 4.0) always show a time
offset on boot:

Setting date via ntp.
 2 Jul 19:20:17 ntpdate[186]: step time server 216.46.1.2 offset 17830.926129 
sec

The time offset is always within a second or two of that same
magnitude, just a few minutes less than five hours.  (Five hours is the
offset from EST to UTC, and I'd suspect that of being relevant except
that we're now on EDT, not EST, so our offset is only four hours.)

Any idea what's going on there?  Does it indicate a problem I should
care about?  It doesn't seem to be causing any other obvious issues,
but I distrust weirdness I don't understand.

                                        der Mouse