Strange interviews - anybody knows?

I had two phone interviews the other day. The project lead and another team member interviewed me separately on the phone.

I think the interviews were a little weired. Both interviewers didn't use up the full 30 minutes. Both finished only with 20 something minutes. They asked me some questions like "Tell me about yourself, what projects you did before...." nothing unusual.

They all sounded very nice and friendly. They didn't really grill me. I felt pretty good about the conversations too. The team lead even said "I think I got enough information about you. You have very impressive background..." when I asked him if there is anything he would like me to explain more.

But then I kind of wondering maybe they were just interviewing me because they have to interview certain number of candidates. And they probably had a person they want to hire already.

Anybody had similar experience? Or know what is going on here?