Why is Firefox giving me inconsistent warning not to go to www.healingwell.com?

This past Friday morning, May 29, I tried to access www.healingwell.com which I have always been able to do. But this time Firefox gave me a red screen with message: "Firefox blocked this page because it might try to trick you into installing programs that harm your browsing experience, for example, by changing your homepage or showing extra ads on sites you visit." And same message again over the weekend. But yesterday, Monday June 1, I was able to access that website, and all seemed normal. Why did Firefox give me that message on Friday, but not yesterday or today?