Hi sentix,
Sorry for that hassle due to a bug to early CBSubs 2 versions. My guess is that you have a very old CBSubs 2 version on your site.
That bug already got fixed in "newer" CBSubs 2 versions, and are definitely gone in CBSubs GPL 3 and 4. CBSubs GPL 3 is a hassle-free unlimited upgrade that we highly recommend to all CBSubs 2 users, specially with expired maintenance. With your Developer membership you have access to CBSubs GPL 3.
As a courtesy, as you have an active Developer membership, to stop those emails from your site to super-admins right now I have changed the license limit.
Please consider planing to upgrade to CBSubs GPL 3 in 2016, as your CBSubs 2 maintenance period is expired and CBSubs GPL 2 is not maintained anymore.