My bank paid off my garnishment when I didn't have enough funds to cover it. Am I liable to the bank for the rest

Yes, it is uncommon, how much extra did they pay ? Are you sure they actually paid it, or did they pay money from the account and other bills or check written not cleared yet will start bounsing

No I had no checks out and they got all my checking and savings which was like 4800 and they paid the other 3000

What a minute. Are you saying they received a writ of execution for 7800 but you only had 4800 yet they paid the full 7800?

Yes

That was a mistake on the bank's part. You should not be responsible for it, it is up to them to get it back from the plaintiff. On the other hand you still owe that $3000 to the plaintiff.

I guess and I don't mean wrong, Are you sure they paid it, not merely just showed your account with a negative balance, often they don't pay it, but will show it as an amount owed in your account so if you deposit any money it goes against the balance of the garnishment.

So in general your account if you looked at the balance would show a negative balance, but did not mean they paid it.

You need to go talk to the officer of your bank to clearify it.