Should a deviated septum be corrected during rhinoplasty if there are no breathing issues?

 Everyone has some degree of septal deviation, but the degree of the deviation will determine whether not there's any symptomatic issues. A very mild the nasal septum should probably be left alone. A moderate to significant deviated septum should probably be repaired, since it will possibly cause nasal obstruction when the nose is made smaller. 

This is a very common and a very good question.  Unless the bony nasal vault narrowing that is planned is very significant, in my experience it's not necessary to fix a non-symptomatic septal deviation, but you have to be seen in person to really get proper recommendations. Be sure to discuss your goals and concerns with your board certified plastic surgeon and consider the pros and the cons. Be certain your surgeon is properly certified.  I've attached a link where you can start your search. 

If you have a deviated septum it should be fixed during rhinoplasty. There is no way to predict whether it will become a problem after making your nose smaller. Furthermore, if your nose is deviated, leaving the septum crooked will increase the likelihood of persistent deviation post operatively.