Why did I burst into tears after I did yoga today?

I've been doing a weekly yoga class for about 2 months now and today when I left I felt really strange and I suddenly started crying but I didn't know why. I felt fine before and I don't have any one thing in particular that I've been worried about or has been causing me a lot of stress. After I cried I felt very disoriented and then some little stupid thing happened and I couldn't stop laughing. What the hell.