OK, that one I've seen. What it comes down to is if you open your info window to verify badges on a character, log out to switch characters before Sentinel finishes verifying all of the badges, and log your next character in, the remaining badges that still needed to be verified will be verified, but they'll be added to the character you just logged in, not the one you logged out.
I think the next version of Sentinel addresses this issue, but I'm not entirely certain.
Until then, the only ways to avoid this are to either verify each character's badge count before logging out to log in the next character or shut down Sentinel between characters. (I recommend the first option.)