Did you know Facebook has a hidden folder. People who are not friends with you on Facebook can send you messages and they end up in this hidden folder.
Be Social, Get Success posted a detailed set of step-by-step instructions on how you can find your secret messages on an iPhone.
If you are an Android user, I found a set of instructions on CNET.
Take a minute to check out your Facebook hidden messages. They could be from a new client trying to reach you.