PhD stipend continues being paid I graduated with a PhD after 2 years (I was very efficient) and even though I have already received my degree and moved out of town, I'm still getting a stipend deposited into my bank account. I contacted my advisor about it but my advisor didn't reply at all, so I don't know what to do about this. Is there a minimum funding requirement or something like that? Or is it just a mistake? What to do now?
Contact your department, CC'ing your advisor.

It happened to me once: I was paid over the summer by my department even if I was out of the US for an internship at a company research lab in Europe.
I came back in September and found additional money in my US account. I told our administrator. she figured out what happened and she told me that in case I had already spent the money, the department would have found a way to ensure things would get straighten out with the university. 
I still had all of it, so I just wrote a check to the university to return the money.