That's weird. I was just awarded a badge for the tag "binomial coefficients" even though I only have 88 total score in that category. It is some sort of software error?
Update Well, now my score has jumped up to 100. I don't know what is going on.
This answer of yours has the score of 12. But the question to which it was posted happened to be from an ongoing contest, and as a result, your answer was temporarily deleted. It was undeleted 14 hours ago.
After the undeletion, it took some time until the score-totaling and badge-issuing processes ran. To complicate this a bit further, your profile page is not generated anew every time it is viewed; the software will often serve a cached version of it. This makes it possible to receive a notification about a badge before having the change reflected on the profile page.