I received a number of calls about a security problem

The calls are scams from criminals trying to steal your personal and financial information.

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support

They are scams to try and get you to reveal your account login information. Apple will only fall you if they are returning a call you first made to them.

Plus, you can always verify your own account is secure by simply checking it at https://appleid.apple.com. Note the https indicting it is a secure connection.