@MosheP. ah. I think that's the "favorite tags" highlighting. Stack Exchange highlights questions that are tagged with any tag you've marked as a "favorite" (over on the right side of the page, near the top). The trick is that the engine wants everybody to have at least one favorite, so we all get
halacha (I guess because it's the one with the most questions; not sure). In other words, it happens to everybody. :-)