COPY..FROM question on 7.3

Trying to import a 4 column tab delimited file into Pg 7.3.  As it stands,
the last line contains only the first two columns.  I would expect that the
import would only update the first two column like it did in  Pg 7.2.x.
However, I get an error message Missing data from column "X".
Is there something I can do to avoid the message?
TIA

Patrick Hatcher
Macys.Com
Legacy Integration Developer