Mine rang once also - however, I read about a scam where people hit call back and it goes to an offshore account that then bills you hundreds of dollars for "services". Basic rule, if was important, the would leave a message.
Called them back , the lady said she has a $100 gift card for me , that they got my number off one of there web sites. She said all i have to do is pay the $4.95 shipping charge BUT i have to use my Debit or credit card. She promissed me over and over that they would only charge me once. This lady really wanted my credit card number. I didn't give it to her , and if you did you should cancel the card.