aggregate functions and timestamps in JDBC, possible bug?

Hello,
I have a problem with PostgreSQL JDBC driver when using timestamps.

Consider this:

CREATE TABLE xyz (
starttime timestamp not null,
endtime timestamp not null
);

INSERT INTO xyz VALUES ( '2002-08-1 03:00:00+03', '2002-08-1 06:00:00+03' );
INSERT INTO xyz VALUES ( '2002-08-2 03:20:00+03', '2002-08-2 06:30:00+03' );

Then do:

SELECT SUM(endtime - starttime) FROM xyz;

And you'll get:

sum
-------
06:10
(1 row)

(Which means 6 hours and 10 minutes).

Then try to read that field using JDBC using something like:
java.sql.Timestamp ts = rs.getTimestamp(1);

And you'll get my problem:

Bad Timestamp Format at 2 in 06:10
at org.postgresql.jdbc2.ResultSet.toTimestamp(ResultSet.java:1705)
at org.postgresql.jdbc2.ResultSet.getTimestamp(ResultSet.java:398)

I am using latest stable JDBC driver from the http://jdbc.postgresql.org/download/pgjdbc2.jar
md5 checksum for my current version:
f4ed2deaa88e16e79ccfa1c5b1f5ca22 *pgjdbc2.jar

Any ideas, tips, help? Anyone know how to get the expected timestamp?
(In my mind it's a parsing bug in the driver, but I let somebody else make the judgement.)

Thanks for any help,
Tomi