Bad ink?

As my class was printing the second color of their reduction prints, my ink started doing funny things. The ink would roll off of their printing plate as they tried to add new. There was plenty of ink for rolling. It hadn't been left out too long. This didn't happen with my first class that printed. This ink was left in my school from the previous teacher when it used to be a middle school, meaning I have NO idea how old it is, except at least two years. Does it sound like bad ink? Does that happen? Feel free to offer suggestions/opinions. I only have a little bit of the black ink left, but I have a lot of other colors that I am a bit worried about.