I made homemade alfredo sauce; now it's a solid? Is it still safe to eat?

I made fettuccine alfredo Tuesday. I made a 1-pound box of pasta and followed a recipe for enough sauce to go with that much pasta, but there were only two of us eating, so I have leftovers. I refrigerated the sauce, but it turned into a solid by Tuesday night. When I reheated part of it, it turned back into a sauce and seemed to taste fine. Is that normal? Can I still eat it, or is it going bad? If it is still fresh, how long will it last?