Tennessee Oncology interview questions

While in the interview, it felt like i was asked appropriate questions and i was given a tour after about 30 minutes of interviewing. Then i was called to say another candidate was chose. I thanked them for the opportunity, but asked how the decision was made so quickly and the recruiter was unsure. A week later i received a call saying i got an offer? By that time i had already accepted an offer. Seemed to be an issue with communication between staff and recruitment.