It is normal for your subscriber count to fluctuate a bit, so I wouldn't worry about it as long as there wasn't a significant drop. If you go to analytics and see that people are unsubscribing on a specific video, then maybe you could look into that video to see what is up with that video to see if something specific might be causing it. But overall, it is normal for your subscriber count to fluctuate a bit especially early on. As your channel grows bigger, you won't notice those few subscribers unsubscribing as much because more people will continue to subscribe with time and efforts.