Should I be worried about this series of events

I had a phone interview for a job last week. A couple days later I received an email with the scheduled time for an in-person interview with a Google calendar event immediately followed by an email changing the date, but no calendar event. I followed through with an email and did receive a calendar event for an in-person interview on the revised date, though at a different time. I know other people applied for this position.
Should I just believe this was human error or should I take it as a sign that they are more interested in other candidates and wont pick me?

There are plenty of possible reasons they could have changed it. It could just be working around the schedules of everybody who's going to be at your interview. It's doubtful they'd have you come in for a second interview if they weren't seriously considering you for a position.