I applied for Mechanical Engineering department for Master degree. I got email for scheduling Skype interview from the faculty and next week I had interview with the faculty. The faculty interviewer is the one I referred on my SOP as whom I want work with. But he told me that that was just general interview for whole departmental level, not just for his lab. He told me that they don't usually interview like this for Master applicant in their department but policy was changed from that year. The interview was really casual around 30 mins interview in very casual atmosphere. I just briefly talked about my prior research experiences and he asked some questions. It took more than 2 months to be declined and thought I was on the wait list. Hope this would be helpful for you guys!