Yep, this is a variation of the cell phone PIN scam. What happens in that case is you buy a prepaid cell PIN from a newish Ebay seller, then you apply it to your account, and it works fine. Then 1-2 months later, the cell phone company reverses the amount from your account because the PIN was purchased with a stolen credit card and the card's owner disputed the charge. You're out money.
Just ignore their pleas and leave the money in your paypal, because it's likely to be withdrawn from your account by Paypal later when they realize it was a fraudulent transfer. Then unlink your checking account from PP.