Look at the stats page for this beer and you will see the spread of scores (indeed you are pretty typical) and also that you are the first to rate it since 2014. No doubt there has been a slight rejigging of the algorithm since then. It appears that the application of the new algorithm doesn’t happen sitewide but only when beers are rated or rerated. So your rate not only counted but kicked in changes to the scoring system.
With unpopular (on RateBeer) styles it is possible for perverse things to happen to score because the algorithm “guesses” a normal score of 2.75 (or something like that) which stops things like imperial stouts getting really high scores with few ratings but actually biases the style ratings of pale and most other lagers up for examples with few ratings. But the main thing here is you were the first to rate this for a while and you bumped it onto the new scoring method.
Can also be that a beer has been moved there, or an alias has been done to that beer, but the admin forgot to hit the “fix score” button after.
Then when you rated the score did get fixed, which happens for every rating normally.