Not necessarily. Generally, if your bank credited your account, it can later reverse the funds if the check is found to be fraudulent. You should check your deposit account agreement for information on the bank’s policies regarding fraudulent checks.
Fraudulent checks may be part of an overpayment/money order scam. This is an example of why you should never accept a check from someone you don't know. The Office of the Comptroller of the Currency (OCC) has issued a Consumer Advisory that contains more information on such scams.
As the payee, it's generally up to you to pursue the person who gave you the check if you want to seek reimbursement. If you think you have been targeted by a scam, you should file a complaint with the Federal Trade Commission (FTC) on its website or by calling (877) 382-4357.