Did you set up your AOL account directly on the iPad, or was it set up for you when you synced for the first time?
If the first, go to Settings > Mail, Contacts, Calendars, select your account and delete it. Then add your account again and choose the AOL option. I'm pretty sure this will set you up as an IMAP account by default, and that should cure your problem.
At least I hope so. AOL offers both IMAP and POP3 accounts. It would be a crime if it was setting up POP when IMAP is available.
If some one who actually uses AOL knows better, please correct me.