Can an employer withhold training pay from last check?

I gave one week notice before I left my last job, I recieved my final check and my employer withheld money from a traing class that I was sent to a few months ago. I was never told I had to pay for the class if I left, nor did I sign anything saying I had to pay it back, just heard something about it through hear say. They also took back the hours they paid me to go to the class. Is this against the law?