Snape Stuns Flitwick: WHY? was: CHAPDISC: HBP 29, The Phoenix Lament

[rtbthw_mom]

No: HPFGUIDX 164141

Snipping great summary, and skipping most of the questions because
better minds than mine have come up with great answers, but I wanted
to comment on this one because I had an idea and haven't seen it
mentioned in this chapter or in the previous one.

>  
> 3. Assuming Hermione's account of events in Snape's office is 
> accurate, what do you make of her and Luna's gullibility? Are you 
> annoyed that they didn't realise immediately that Snape had 
> stupefied Flitwick and try to stop him? 

Putting aside Hermione's and Luna's gullibility, I have always
wondered why in the world Snape would feel the need to Stupify
Flitwick, duelling championship notwithstanding.  Flitwick's stated
purpose was to wake Snape and get him to help with the fight - Snape
should not have had any way of knowing what was coming.  For that
matter, what in the world was Snape doing asleep??  He's always up at
all hours: nearly every time Harry has been wandering around Hogwarts
after hours, who does he run into??  Back to the issue at hand,  I
have recently come to believe that Dumbledore had told Snape where he
and Harry were going - well, maybe not *where* they were going, but
what they'd be doing that evening, and that DD expected to have health
problems afterwards, just as he did after finding the ring horcrux.  I
believe that DD asked Snape to sleep while they were gone, and the
plan was for Snape to stupify *Harry* when DD sent Harry to get Snape.
 That would have put Harry out of the way while Snape could tend to
any of DD's 'injuries.'  But instead, Harry was unable to get to
Snape, and McGonagall sent Flitwick to find Snape. . .

In the overall scheme of things, this is really unimportant, I know. 
Am I completely off my rocker, or does this make sense to anyone else?
 Thanks for any comments -
Pat