Why does emailing a song from iPad Garageband distort the music?

Question

When using Garageband for iPad (which is amazing by the way), when I export to iTunes, the sound is perfect.  When I use the email export function, I find that there are almost always often distortions, artifacts, or ommissions.
My process is usually to make the song, make a screenshot, switch to photoshop, rotate the screenshot, go to Photos, copy the screenshot, return to Garageband, export to email, wait for the encoding to take place, paste the photo beneath the song in the email, then send the email (usually to posterous). 
If I export through my mac in iTunes it seems to work flawlessly.

Answer 1

I've found that the AAC file exported through iTunes or through email are exactly the same... however... I've noticed this: Sometimes when I first boot up iPad garageband and start playing a song, I get distortion, dropped notes or ends of notes. If I stop the song, rewind and play again, it sounds fine. Just recently I booted up garageband and WITHOUT opening or playing the song, I exported the AAC (.m4a) file to iTunes and also emailed it to myself. Both versions had chopped notes, stuttering, etc. throughout the whole song!!! On a hunch, I went back to garageband, opened the song and played it. Sure enough, at the beginning it played like sh*t. When I touched the 'go to beginning' button and played again, it played fine. I then closed the song and exported as the above procedure. Both files played fine!
Maybe it's my earbuds but the imported songs sound duller than when listening to the originals on the iPad.