In this instance you are probably incorrect (assuming you actually have an email account withAOL!!!), although your paranoia level is healthy!
It looks like AOL is instituting some form of certified email, hence the requirement to modify your client / access mechanism.
Goodmail Systems Home Page, Home of CertifiedEmail. Creating Trust in Email.
But it always pays to log in directly to your account, not via the link in the email, to corroborate the email and ascertain the details.
SD