Is this error correct/possible?

Hi,

I have a database which is created in PostgreSQL 8.0.3 which is filled
with a PostgreSQL 7.4.7 database backup. Both databases where created
with SQL_ASCII.

Running a query against on of the tables gives this error (with the
pg74.216.jdbc3.jar and postgresql-8.0-312.jdbc3.jar drivers):

"Invalid character data was found. This is most likely caused by stored
data containing characters that are invalid for the character set the
database was created in. The most common example of this is storing
8bit data in a SQL_ASCII database."

Inspection of the row (using pgadmin3) shows that there is the char "ü"
in a char(40) columns.

Questions:

1. Is a "ü" allowed in a SQL_ASCII database and a column of char(40)?
2. If so, is this a JDBC bug?
3. If not, is this a PostgreSQL bug, allowing a non-allowed character in
a column?

TIA

Joost