Sounds like a binding nut. In other words, the string is catching on the nut. Thus every time you do a bend, the string will catch as it is bent and come back flat. You can either put some lubrication in the nut slots (graphite, nut lube, etc.), or replace the nut with a better one. I'm not sure how good the nuts are on the RGAs, so a Graphtech nut may or may not be better.