resultset.first() untrappable error

the following code frag has recently started bombing in a bean. It
produces no trappable error I can see (SQLException, Exception,
RuntimeException all fail) and is bombing at the ResultSet.first()
function call. Its using redhat 7.3 postgres jdbc pg73b1jdbcX jars.
The db is 7.3.2. jdk is sun
hotspot 1.41-b21. The sql works in a file with hard coded customer id.

        query = "SELECT TO_CHAR(break,'MI9999990D99') as value," +
                    "       TO_CHAR(discount,'MI9999990D99') " +
                    "  FROM customer " +
                    " WHERE id='" + custid + "'" +
                    "   AND discount > 0 " +
                    " UNION " +
                    "SELECT TO_CHAR(value,'MI9999990D99')," +
                    "       TO_CHAR(discount,'MI9999990D99') " +
                    "  FROM discountbyvalue " +
                    " WHERE account='" + custid + "' " +
                    " ORDER BY value";

        results = stmt.executeQuery(query);

             // only output discounts if there are some */
            if( ! results.first() ){
        results.close();
        stmt.close();
        return "";
        }

Anybody got an idea why?