My ipod is deleting music?

My ipod touch seems to be deleting music on its own. I bought songs a few months ago ( via my ipod), and it now the songs are no where on my ipod. I plug my ipod into two computers. One that has itunes and one that doesnt. The one with itunes doesnt sync though. And its only a few songs, all the rest of the songs i bought a few months ago are there. Should I call apple and see what is wrong?