Nagios NRPE check_procs reporting incorrect number

I had a similar problem. check_procs is internally calling /bin/ps axwo 'stat uid pid ppid vsz rss pcpu comm args', it's listing the processes and then counting them. If you have configured nagios to run with a different user, it's using sudo to execute the command. And here is the problem. If you type sudo ps -AF | grep sudo, some distribution return "grep sudo", others return "sudo ps -AF" and "grep sudo". As check_procs is counting all processes, you will get different results on different machines. Unfortunately I do not have a solution yet how to force check_procs to not count sudo processes.

Sounds like the version of check_procs in Lucid is buggy (or at least has changed it's behaviour); the fact that it's always finding one extra suggests that it's doing a substring match on any part of the process name and arguments and finding one of the processes associated with running the plugin. Worth reporting a bug to Ubuntu about it.