I wouldnt worry about it if it is nothing serious. In about a month or 2 your jag is gonna put that con it its place.
Also, it might not be a bad thing if your looking to add other fish later. If that con gives your jag a little taste of submission, the jag may end up growing to be a mellower jag (as much as can be said of jags) and let you keep him with other tankmates.
I have a con who thinks he's the boss and used to pick on my jag when it was still like 3-4 inches but now that the jag is 10 inches and the con is still 4-5 inches it doesnt work that way anymore.