That's the same spot, in P/SS... remember, Harry tried on the Invisibility Cloak for the first time after receiving it for Christmas, and he watches the Mirror of Erised... the next night, he and Ron go, and the next night, he goes alone again... That's when he runs into Dumbledore, and at the end of the chapter, after Dumbledore tells him that the happiest man alive would see himself exactly as he is, Harry asks what he sees when he looks into the Mirror of Erised.
"I? I see myself holding a pair of thick, woolen socks."
Harry stared.
"One can never have enough socks," said Dumbledore. "Another Christmas has come and gone and I didn't get a single pair. People will insist on giving me books."
It was only when he was back in bed that it struck Harry that Dumbledore might not have been quite truthful. But then, he thought, as he shoved Scabbers off his pillow, it had been quite a personal question."
I wonder, too, if it doesn't mean the freedom thing, if Dumbledore is as close as it is possible to get to being the happist man alive (seeing himself only as is) if his only greatest desire is to have another pair of socks....

I think I stick more to the freedom theory, but it's a thought... He doesn't seem the type to really desire the things people usually desire...