Yes. It's a question that could be verified by a third party without too much difficulty, and I think Quirrell would strongly disprefer to be caught lying. Making Harry mistrust the note-sender may be to his advantage, but I don't think it's enough to outweigh the downside.
If he did (somehow) know about the note before Harry told him about it, there could well be some plausibly deniable reason he could later give as to why he was only able to say "London" and not "The Chancery Building"
I'm not sure what potential risks portkeys could have over long distances (in Canon Potter, to say nothing of MOR Potter) so this might not actually be evidence of trickery on Santa Claus' part, although since neither of the two brought it up I'm probably just fighting Santa Claus not intending to send Harry to Salem because that's just what Eliezer wants us to think.
Update: Discussion has moved on to a new thread.
After 61 chapters of Harry Potter and the Methods of Rationality and 5 discussion threads with over 500 comments each, HPMOR discussion has graduated from the main page and moved into the Less Wrong discussion section (which seems like a more appropriate location). You can post all of your insights, speculation, and, well, discussion about Eliezer Yudkowsky's Harry Potter fanfic here.
Previous threads are available under the harry_potter tag on the main page (or: one, two, three, four, five); this and future threads will be found under the discussion section tag (since there is a separate tag system for the discussion section). See also the author page for (almost) all things HPMOR, and AdeleneDawner's Author's Notes archive for one thing that the author page is missing.
As a reminder, it's useful to indicate at the start of your comment which chapter you are commenting on. Time passes but your comment stays the same.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: