Ahrefs webmaster tool question

I have a free account of the tool in the title. Back in July, when I registered I ran a health check on my website and got a score of 47. Since then the only thing I did was to re-submit the site map to google, updated the plugins and the theme and pretty much forgot about the all thing. Yesterday I checked the site again and the health score is now 97. What could have happened? Why the score changed so much?