Nagios check to see if a certain IP appears in a trace route
Your use of $locate as a regular expression for grep is sloppy.  If $locate is 2.3.45.25, for example, a hop through 70.233.45.251 would be considered successful.

I suggest using grep -F " $locate " — with -F to interpret the argument as a fixed string rather than as a regex, and with spaces before and after the IP address.