It certainly seems that everything for the most part is coming along very well.
Shortness of breath and fatigue, if they are new, are however, signs which need to be watched. They could be lots of things, asthma, lung problems, Congestive heart Failure or just plain being tired.
If it were my husband, he has had three open heart surgeries and two lung surgeries, I would be watching him carefully.
Not that I want to alarm anyone, but with people who have had heart surgery, everything means something.
There is something called a Peak Flow Meter, which can measure the lung volume every day and you can chart it. That way you would have a record of lung performance and would be able to see if there is indeed a trend.
If the doctors are not concerned, it's probably just one of those things, but you keep an eye on her anyway.