I'd get another one and use it for a while to see if the issue vanishes.
I have a generic 16 GB micro SD HC memory card that I used in a Canon PowerShot SX40 HS digital camera. I do not use the camera very often, but I had problems with the memory card twice within the last several months. On both occasions the camera gave me a memory card error and would not let me take pictures.
The first time I was still able to read the memory card on my PC using a memory card reader, so I could back up all of the files (most had been saved on the PC anyway). After reformatting the memory card worked fine.
Today I had the same problem again, but this time I could not read the card on the PC either. Again, reformatting go things back to normal.
Is this a sign that this card is done for and I should replace it? If so, I'll probably spend a little extra and get a memory card with a lifetime warranty.