That's a Chinese hamster for those who want to know. (: They are known as mouse-like hamsters due to the longer length of their tails compared to most hamsters.
Your hamster was fine. If you picked him up suddenly, you may have startled him. In the wild, the hamster's defense mechanism is to freeze if a large predator swoops nearby so that they aren't seen. :)
That's a Chinese hamster for those who want to know. (: They are known as mouse-like hamsters due to the longer length of their tails compared to most hamsters.