Bumburglar

So I replaced my rotors/brake pads last weekend and was careful to put it back together just how it was before I dissembled everything. Used anti seize lubricant before I put on the now rotors. Used brake cleaner to clean where the rotor goes, on the rotor before I put it on, etc well now I’m hearing a weird sound that seems to be coming from directly under the trunk. Sounds like something is loose down there (loose down there LOL) jokes aside, at first I thought it was my car jack and removed it only to keep hearing it. Any ideas of what it might be?? When I jacked up my car I did it from the sides, near the rear tires and only one at a time. Never heard it before until after the weekend project. Please help