Thinking back to the Remembrall incident, it's likely Harry has memories of Voldemort that are slowly coming out...
The far easier explanation for this, which does not have all the problems of being an ridiculousness easy and yet unknown method for detecting of Obliviation having occured is that Harry forgot that he is strictly forbidden to use a Time-Turner in view of the public!
That makes sense.. but immediately afterward both Harry and McGonnagal thought it was unusual how bright the remembrall shined; neither seemed to think it was solely due to the use of the Time Turner:
"The Remembrall was glowing bright red in his hand, blazing like a miniature sun that cast shadows on the ground in broad daylight."
and
""More importantly, why did the Remembrall go off like that?" Harry said. "Does it mean I've been Obliviated?"
"That puzzles me as well," Professor McGonagall said slowly. "If it...
The new discussion thread (part 15) is here.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 82. The previous thread passed 1000 comments as of the time of this writing, and so has long passed 500. Comment in the 13th thread until you read chapter 82.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13.
As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.
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: