Loading MathJax Config popup

I don’t think this happened before, but with MathJax support turned on, I see a gray popup box on the lower left corner whenever I navigate to any link:

Loading [MathJax]/jax/output/HTML-CSS/config.js

I don’t even have any math on any articles yet; I was planning on using it in the future. With MathJax support turned off, the popup doesn’t show.