DG834G and GRC port testing

I wonder if anyone would be interested in commenting further on my findings
between two different releases of firmware for the DG834G.

The two I have been testing are 1.05.00 and 3.01.25 (latest).

I have used both these versions of firmware to test the DG834G with GRC.com
Sheilds Up security tests.

I have opened up ports 21(ftp) 80(http) and 443(secure http) using both
versions of firmware on the same DG834G unit.

Would anyone care to suggest a reason why GRC.com SheildsUp, reports a true
stealth using 1.05.00 on open ports 21, 80, and 443, whilst the same test
using the latest 3.01.25 firmware gives 'true stealth failed' when probing
open ports 21, 80 and 443 ?

I have been using firmware v1.05.00 for more than a year with ports 21, 80
and 443 open and always got 'true stealth' when testing it with grc.com, but
now using the latest firmware, it is reporting them as open (true stealth
failed).

Its obvious to me, that they must have always been open when using 1.05.00,
as the services on these ports ere always accessible from the internet, but
why were they always reported as true stealth by grc.com using the earlier
firmware, but not with the new firmware?

From a security point of view, I prefered grc.com telling me they were
closed, as this made me feel a bit more secure against port probing and
hacking attempts.

Any comments on the above would be most welcomed, and would hopefully clear
up why the new firmware is giving different results to the old one.

Thanks

S