Not too familiar with itunes, as in my own opionion is the worst media software for audio, i use media monkey ftw. Make sure that your id3 tagging for audio files is attached to the actual song file and not the folder where you keep your music that way when you transfer files the album art is with you. Also you use the word usb so i assume that your phone is plugged into the computer when listening to music, when the phone is plugged in some info stored on the micro sd card may not be accessible including the album art.