Ok, your users are not expired yet due to Grace Period on some of the plans your users are subscribed to. For example Concession has a 2 month grace period. This means they won't truly expire until that grace period ends.
I believe the mailer is supposed to ignore the grace period, but it looks like it's also considering the grace period when processing the queue. This means their actual expiration date is 2 months after what you see in CBSubs > Subscriptions. You have a mailer configured for 1 month before expiration, which several users should receive around 2015-04-30 or 2015-05-01.