SD Worx Program Manager interview questions

I got contacted by HR via email, and a call has been scheduled. It went smoothly and only 1 day later I've got contacted again for a formal interview with the team leader + head/director of the department. Also this interview went smoothly, I quite enjoyed the conversation, they seem to promote the company as a good working environment. Before it was finished, they have asked for a follow-up meeting/interview in the next week, which I agreed. But then 3-4 days later, I got an email to say that they chose another candidate. It is all fine, but nevertheless it was very strange. Normally the interview is wrapped-up as "we will discuss internally and let you know", but this time they quickly emphasized that they wanted a follow-up meeting with me, gave me couple of things to be prepared, and they changed their mind.