Interview process help

Made a throw away account for this.

Wondering if I could get some help understanding an interview situation I’m in with a boutique bank. Had three phone interviews in a short period of time. At the end of each interview I was told the process consisted of two or three phone interviews followed by an in office superday. All the interviews went pretty well and the firm was very responsive and quick to schedule the subsequent interviews.

After the third interview I felt pretty confident I’d be invited to the superday. Turns out I got an email saying they want me to do another phone interview. It’s a small firm and they have been selling it to me in each round and seem pretty attracted to me. I’ve told them I’m interviewing with other places so need to hurry up a little, but having another phone interview is a little bit of a set back. I have also made it seem like I have other options other than them. What do you think is the reason for an additional phone interview? Is it because they are on the fence with me? Or could it be to make sure I actually am interested in them? Thank you for all the help in advance.