I assume you are using 5.6.18+ since that is when the warnings was implemented. If you use the 5.5 series, it will not have it.
If this is correct and no warnings, that would mean you have the correct version.
To double check the version you have Type this in CLI on each of your APs.
grep regdmn /proc/ubnthal/system.info
It should output like this. US Version