Now the first thing I have to say is that Paypal caught this problem and put it right reasonably fast BUT this is why I do not trust Paypal.
As you know, to have a Paypal account you have to give them access to a bank account, whether or not you intend to use their "instant banking". (As far as possible I only use my Visa card through Paypal.)
So I set up a special bank account, where I only keep $20.00 or so at a time.
Just as well. Somebody hacked into my Paypal account and tried to pay Skype 50.00 Euros directly from MY bank account. It went through, but put my account firmly into the red, which triggered flags a day or so later, and Paypal limited my account, reversed the transaction and notified me.
I then had to spend a few hours sorting this out and changing passwords and getting re-instated, so that I could actually use the account again for some purchases. I also had to make sure the bank didn't charge me a dishonour fee.
Yes, the AU Paypal staff were accessible, helpful and diligent. But it shouldn't have happened in the first place.
So, DON'T let your main bank account be the one you register with Paypal. There could have been a lot more money involved than just a few dollars.