Percona Backup + zenoss

Have a weird problem where if I run innobackupex (v 2.4) and also have zenoss monitoring the database (5.7) I see memory usage increase until, a few days later, oom-killer will bring mysqld down. Total Innodb data size = 37G. Total memory on server = 16G and innodb_buffer_pool_size=10G

Has anyone seen anything like this or have any ideas? Thanks