Can't get a clear picture

I joined this software company before a year and was put on a live project immediately. I had to undergo training from one of the team members before i could start working. I looked at this as an opportunity to know more about project. So as i got to know about technology, the team mate started expressing his views about other team members i.e. developers, in how they would pressurize you to work and some other negative aspects. I was sort of concerned now and formed a negative impression about the people on this project. So i made a decision to keep distance with them. Soon it was shocking to see that the team member who told me all these was himself mingling with rest of the team as if all were in good sync. I could not get out of the negative impression i formed initially and so i always felt a bit wary when relating to others.
Same thing happened with another team member who kept complaining to me that developers(other team members) were mean to us and that they were to blame for the faults. However, he became a loyal dog to them (developers) when they asked him to do something. It was as if they were friends and had good understanding with each other. And i was the one who was left out. I was clearly shocked at this double faced behavior of my co-workers. I would like to know if this type of behavior is common. Also is it me who is stupid in not being able to understand this office behavior?