DD not reacting to Hagrid's mention of Sirius?

[mysterious_one1987]

No: HPFGUIDX 184163

Hey there, I'm new here, so please excuse any mistakes I may make,
although they may get taken care of by the moderators.  I was reading
an old forum today where someone posted a question that was never
answered, and after spending the day searching for an answer, I have
nothing to show for it, except finding this spectacular group that
I'm sure will provide me with some insight :)

In SS/PS, Hagrid turns up at Privet Drive with Harry, where he meets
McGonagall and DD, as we all know.  They proceed to talk about the
defeat of Voldemort and the death of the Potters.  Hagrid states that
when he went to pick up Harry, he saw Sirius there and borrowed his
motorbike.

Now, the Potters are already dead, and DD knows that a Fidelius Charm
was put in place to protect their whereabouts from LV.  Dumbledore
also presumed that Sirius was the SK for the Potters, so it would
follow that Dumbledore thinks, as everyone else does, that Sirius
betrayed the Potters.  So why doesn't he react at all when Hagrid
tells them that he saw Sirius?  I mean... maybe he is trying to
protect Hagrid's or McGonagall's feelings at this point, since the
death of their friends is so incredibly fresh in their minds, but I
do think that JKR would have mentioned SOMETHING, whether it be a
look, a small movement, anything by DD here, as she usually employs
these sorts of small details to hint at something much larger.

*I'm sure this question has been posted before, but I couldn't find
it in anything recent.  Please forgive me if I'm about the 100th
person who's wondered this.*

~mysterious_one1987