With LDAP you typically don't want to distribute your passwords all over - password management is on one side, e.g. on LDAP, and the password policy that applies there should carry on everywhere. When you change your password on LDAP, would you want to be able to log in to your portal with the old password? One positive aspect on having passwords in a separate system (like LDAP) is that they can't get loose should there be any security issue in your front end application (like Liferay, but by far not limited to it).
In fact, I prefer to add an SSO system, so that Liferay never even sees any password. Further, passwords are hopefully stored in a salted&hashed way, so that you can't "just get" them out of any system. Granted, during login without SSO, Liferay knows the password, but I'm actually happy when that's not written to the local database.
If you rely on your Liferay database to have your correct passwords, you should be changing your architecture. To me your description sounds like "yay, works as expected".