timestamp 0#0 on modify with only remove-value

Hi
Is this by design or a miss somewhere?

When I modify an object by changning an attribute value or by adding a new value I get a proper timestamp value in the timestamp attribute on the modify element.
Example:

timestamp="1328863958#3"

But when I delete a value and do nothing else with the object the timestamp in the resulting XDS is:

timestamp="0#0"

Any idea why?

Thanks