iPod Touch App store problem

Hi. I'm having an issue with iTunes/app store on my G2 iPod touch: when I try to buy xplane extreme, it says that my email has changed and to sync with itunes on a computer. I can download free apps and log in fine, and the other day I was able to buy an app, but I can't seem to download this one today. I should mention that I'm not near a computer. Also, nothing has changed since the other day except for an app finally updated (I un-screwed it up). As far as my email address, I did change it about 3 weeks ago, and the screwed up app update happened about one week ago. Should I just wait until I get to my computer or is there some other fix?

If I'm understanding you correctly,I think apple is running this as a security measure. It my want you to purchase via a computer FIRST, to make sure your verified.