Snape knew

[owen]

No: HPFGUIDX 160978

Eddie:
> He showed Harry the memory of Trelawny on the surface of the
> pensieve instead of diving into the pensieve, so we only see and
> hear Trelawny but not the rest of context.  Maybe Harry will learn
> a lot by doing some pensieve diving into this particular memory.
>
> Annemehr:
> Yes, I've had that pointed out to me as being suspicious before.
> *Why* not just dive right in?  Eh?

owen:
May I answer this? We can see the answer in book 6, what happened when Harry found out that it was SNAPE who eavesdropped? He was very angry. THAT my friends is what Dumbledore doesn't want to happen, imagine the reaction of Harry if he ever saw SNAPE in the scene and then Dumbledore just "forgave" Snape... Harry will surely rage at Dumbledore again! He knew that Harry is very emotional...