I have not been able to recreate this.
Can you send me the DDL for the table you are using and an export file with some of that table's data.
When exporting can you run a select from each column and also include casting to CHAR your date columns such as:
SELECT COL1, COL2, COL3, CHAR(COL3) AS CHAR_COL3 FROM TABLE
Also send your xls file that was created in Toad's Export wizard.
What version of Toad are you running?
What version\platform of DB2?
If this gets complex or too cumbersome - I recommend opening up a support ticket.
Thanks - Jeff