Synchrony Customer Service Representative (CSR) interview questions

I was called for a phone interview, the lady asked me about 6 general question such as why am I good fit for the position etc... So after the interview was done she put me on hold for about 2 minutes, and told me that I selected for a on site interview. Once I arrived at the location, I waited for about 20 minutes before I was greeted by one of the hiring managers. The interview was very lengthy, and to my surprise the interviewer asked me questions from a stack of papers, as I answered the question he wrote my answer down, and when I gave my answer he wanted my elaborate as much as possible. After 45 minutes my interview was over, and he stepped out the room. 5 minutes later I was offered the job pending background check and drug screen. I knew I didn't have anything to worry about. After 2 and a half weeks I was called from HR stating that they had to decline my employment offer due to an inclusive drug screen. I was shocked because I normally drink a lot of water. I wasn't even offered to retake the drug test. So I missed out on a good job offer.