Summer time installation in hot humid weather can certainly swell the wood a bit. Then when you heat your house to desert dryness in the winter the wood will shrink. That's the nature of the beast. But you can do lot's of things to minimize this problem. Humidify the house to at least 40% relative humidity during the heating season. And air condition during the summer.
You will need to measure this with a hygrometer, else you will not know. Buy a wet-dry bulb type from http://www.e-sci.com prod# 848N635. Try from now on to keep your indoor humidity to between 40-60% ALL year round. Museums keep their indoor relative humidity to 50% plus or minus only 5%. And they have NO seasonal movement with in their wood furniture displays.
This is especially important for prefinished floor, with their open seams they have much more susceptibility to humidity swings. If the boards are wider that 4" this may be a continuing problem. And lastly if the floor was laid on a thin OSB sublfoor, you will always be hearing nails pop. Some thing are normal, like the seasonal movement. And some things like using staples instead of nails, using OSB instead of plywood as subfloor and a general sparsely nailed floor are now the industry standard. And these will also contribute to your dilemma.
So, if you want, describe your wood species, how it is finished, what the subfloor is and thickness, and what the hardwood floor fasteners were. Is there an unheated and damp crawl space under this floor. Was the hardwood floor acclimatized for at least a week in the air conditioned finished house (all drywall and painting done). If you can answer all this I can tell you if the installation was defective.
As always your Most humble servant, Joseph, the Wood Floor Doctor.