Not necessarily. While it could be related to a suspension or ban, it could also be locked due to logging in from a different IP address or some other reason which has triggered their anti-hack security measures. Account lock does not necessarily mean account suspension or ban.
Check your email (and spam folder) for any emails from Blizzard. Their should be an email explaining why the account was locked. It has taken up to an hour after my accounts have been locked for the email to actually show up in my inbox.
Edit: "Character lock?" Do you actually make it in to the character selection screen and get that when you try to log in to a specific toon? If so, the only thing I can think of here is related to trials. Say you had an account which was BC enabled. You used a Lich King trial and made a DK. Once the LK trial expires, your DK will no longer be playable. They don't lock characters due to botting, they lock accounts.