Default Device indicates SDCard is full but it's only half full...

Just noticed since I have filled up my SD Card. But seems that when I use my video camera, the phone will start to tell me that it's full and stop recording. But it does this when the card reaches only half full. Not sure what is going on.. but the card is fine. It's a Transcend, 32GB Class 10, HC1.....

Samsung Galaxy S4 (Sprint SPH-L720)
ROM: Still evaluating....
Modem/Baseband: MK2
Kernel: Varies
Battery: Stock

West Coast, United States
Retired devices:
Motorola V600
Palm Treo 650
Samsung Galaxy SII (Epic 4G Touch)
HTC Droid Eris