I-Firefox Isithangami Sokwesekwa

I recently installed Firefox on my new laptop. During install I recall seeing a pop up for McAfee. I think I clicked that I didn't want it. After using Firefox for a little while, a McAfee pop up appeared about being on a dangerous site. (This is one that I have been on numerous times before and my preferred virus protection has not had an issue with it.) Does Firefox automatically install McAfee even when we don't want it? I searched through my apps and found a McAfee Webmaster app and uninstalled it. I have inadvertently had McAfee added on other computers and have had nothing but problems with it. If Firefox wants to associate itself with McAfee, I am having my doubts about what else is being added to my computer. Should I be concerned?