parse error in timestamp function

The following examples from 4.8. Date/Time Functions and Operators fail
with parse errors in PG 7.2:

select timestamp(date '2000-12-25');
ERROR: parser: parse error at or near "date"

select timestamp(date '1998-02-24',time '23:07');
ERROR: parser: parse error at or near "date"

The same examples do work in PG 7.1.3.

Is this a bug?