I've had a user that couldn't login and thought the account was locked. From what I can tell, the account was not locked and had not expired yet it behaved as though it was expired and needed to be reset. Resetting the password with passwd resolved the issue. Maybe someone can point me to something I'm missing.
Here are the details:
This is an application account used on 4 systems and the passwords are manually set to match.

cat /etc/passwd shows as expected:
accountname:x:4101:2100:accountdescription:/sbin/nologin

cat /etc/shadow also shows as expected:
accountname:passwordhash:14122:0::14:::

faillog only showed a latest value for 1 system. All of them showed 0 failures and 0 maximum.
sudo faillog -u accountname
Username Failures Maximum Latest
accountname 0 0 Mon Dec 29 14:30:03 -0500 2008 on IPaddress


chage showed Aug 31 on 2 systems and May 8 on the other 2:
sudo chage -l accountname
Minimum: 0
Maximum: -1
Warning: 14
Inactive: -1
Last Change: Aug 31, 2008
Password Expires: Never
Password Inactive: Never
Account Expires: Never

/etc/login.defs shows:
PASS_MAX_DAYS 90
PASS_MIN_DAYS 0
PASS_MIN_LEN 8
PASS_WARN_AGE 14


/etc/default/useradd shows:
INACTIVE=-1
EXPIRE=

So from everything I can see here, we have policies in login.defs that were likely applied after the accounts were created or the accounts were changed with chage to override those settings. Everything here seems to indicate that the passwords should never expire or become inactive (Maximum -1, Inactive -1).
Am I reading something wrong or missing some other commands that would help me?

By the sounds of it, the accounts hit the 90 definition rule and that took precedence over everything else. If the accounts were created before the rules were put in place that could confuse the system, but if not then I'm at a loss of to why that should have happened.

BTW, my chage for non-expiring accounts says Maximum = 999999. Your's says -1. Not sure if that is an issue or not.

found this info in some articles on web, indicating -1 should mean it doesn't check for max days.

Passing the number -1 as MAX_DAYS will remove checking a password's validity.
Passing the number -1 as the INACTIVE will remove an account's inactivity.