[Freeswitch-users] Limit module using hiredis

I am using limit module as per https://freeswitch.org/confluence/display/FREESWITCH/mod_dptools%3A+Limit and using it to limit number of concurrent calls for a given resource (Unique ID for a group of Source IPs). I am using hiredis module and my redis server is on another box. It all seemed to run fine when I implemented but after few days of running (Freeswitch was restarted but not redis server) I saw that redis entries have minus values against keys. In what condition they will cause entries to be negative?.