Had two stents in in 2011. Everything was completely normal until last night I got short of breath. Was able to settle down but any idea what happened?

Could be other thing. May or may not be related to your stents ... Could be pulmonary - asthma-like attack, pulmonary embolus, spontaneous pneumothorax , if recurs, see your md ...
Coronary artery. Shortness of breath could be meaningful particularly if it occurred after exertion. In the setting of prior coronary disease it suggests a need to see your cardiologist and likely reevaluate your status. If it truly is due to recurrent or progressive blockages the change in symptoms is likely to keep happening or get worse. Other things though, like respiratory/bp issues can explain too.