Notification email shows random file change dates

I recently got two “files changed” emails that says over 1200 files have been changed (/wp-includes, /wp-admin, and /wp-content files, plus files in the root directory). The oddest thing is the “modified” dates listed in the email are all sorts of random dates over the last couple of years! At the time, I was using iThemes Security 4.2.13, on WP 3.9.1.

For example, an email from a July 25, 2014, scan lists:
wp-includes/category-template.php [Modified:] March 25th, 2014 at 2:40 pm UTC
wp-includes/class-simplepie.php [Modified:] November 5th, 2012 at 10:25 am UTC
wp-includes/js/imgareaselect/jquery.imgareaselect.js [Modified:] September 21st, 2013 at 6:43 am UTC
Along with another 1200-some other files.

Prior to these emails, I had not changed anything at all on my WP site or in any plugins (including iThemes Security) for a couple of months.

Any idea what in the world could be going on??

Thanks for a great plugin!

Jamie

https://www.ads-software.com/plugins/better-wp-security/