general: warning: max open files (3636) is smaller than max sockets (4096)

[Squirrel]

This happend since I've upgraded bind 9.21 to 9.6.0.  I've increased the max open files to 4096:

   sysctl -w kern.maxfiles=4096

which shows it resized from 4040->4096

But I guess it's different for bind?  I've googled and found several references to this warning message, but everyone states it's not a problem and shouldn't be concerned.  Some real advice would be appreciated.