Congrats on getting the Epic badge, it is a really hard badge to get!
There are many little subtleties going on that I should explain.
Badges look at current rep levels in the DB
There are certain edge cases where rep levels in the DB do not match the rep report. The rep report show what your reputations should be, not what it is.
The rep report excludes rep which was gained from deleted posts. Also there are a few edge cases where rep may mismatch due to timing of undoing votes and so on.
Badges query actual data in the DB, they may be out-of-sync with the data in the report.
I performed a recalc on your account (which gave you a bit of rep) so I could analyze this all the way through.
The rep report shows a count of the days rep exceeded the rep threshold
So there is a subtle difference here, if you met the rep cap but did not exceed it. The row is not counted in the report:
-- 2011-01-21 rep +200 = 5760 the missing magic day.
The wording for the badge is "Hit the daily reputation cap" not "Exceeded the daily reputation cap"
I think this semantic diff is kind of pointless, the report should probably count the days the rep is met, however I am not feeling brave enough to play with this code at the moment. (please post a separate request if you think this change is important)