Actually these 4 error lines were the only ones until now. And I didn't notice any problems because of this error. The card is working since two days now. I've downloaded a 700MB distro image over wlan to the sdhc and md5sum was ok. No errors occured. Reading from the card is also ok. No filesystem corruption. If you have any specific usecase I should reproduce to force a filesystem corruption, I'll test it for you. Maybe your card is faulty and you should replace it with another class 10 card.