If you have the time and wnat to know for certainty if the card has problems there is a program I use on all my cards to verify the integrity of the card itself. The program is called h2testw.
Download H2testw 1.4 Free - Check your USB for errors with this tool. - Softpedia
This is one link to the program, if you google you can find tons. The program was made by a German individual, but can be had/run in english. When used it will/can be configured to write/read/verify every sector on any sd card type. It takes a very long time to test a 32gig card, but the program does work. I have used it to troubleshoot other cards of mine that have errors.
I too bought my 32 from Amazon. The packaging said sandisk, bulk packaging. The other thing that was recommened in many places is to format the card on the pc and not the phone. I did this, ran the check program to verify my card had no bad sectors. This may not cure your problem, but can at least rule out bad card sectors.
Craig