There's no way to accurately tell what's wrong with your floor without knowing what the moisture levels are. Ideally you should have it tested using a meter with insulated pins that will tell you the moisture level in the top and bottom of each board. The subfloor should also be tested and a thermo hygrometer will give you a reading on the relative humidity in the air.
You're probably referring to cupping where each board takes on a concave shape with the edges being higher than the center. This is generally cause by there being higher moisture in the bottom of the board than in the top.
Buckling is what happens when the entire floor grows and the pressure raises the floor in a section to it looks like a pup tent or a hump.

In addition to the above, can you tell us what type of hardwood (i.e. solid, engineered) and what type of installation method (i.e. nailed, glued or floated) and what substrate (i.e. suspended wood, suspended concrete, concrete on grade).

From your description, I think I was right with buckling. The boards still seem to be flat (each board isn't cupped), but they are lifting like a pup tent/hump. Every couple boards, there is a hump.

The flooring is 3 1/4 inch solid maple. It's nailed.
The flooring is on my main floor, and we have a basement below it; I am going to say it would be suspended wood (engineered joists/beams with 3/4 inch OSB).

I don't know about the moisture; when we had the service manager and he set something on the floor and just said that the humidity in our house was way too high (didn't mention a number). Should we have him back out to test it as you mentioned above?

Attached is a photo of the flooring; as you can see, there is a peak/hump/whatever in the middle of the picture, and the boards on the right and left sides are lower than in the middle.

I would get him back out as you really need to get the issue resolved not just for the flooring but if you have an ongoing moisture problem you don't want to get mold.

Another question: Is you floor installed parallel to the floor joists or perpendicular to them?

That is not serious tenting, but the fact that it appears every few boards may mean that the flooring was skip nailed or installed parallel with the joists.

It's perpendicular to the joists.

When the first hump appeared, I was convinced it was from a joist, but then it started happening all over so I wasn't sure. It's pretty inconsistent; there will be a stretch of about 8 boards with no tenting, then one, another couple boards, a tent, more boards, two tents in a row, etc.

I agree that from what I have seen in pictures, it doesn't look horrible; I am a bit shocked that it's a problem though in our home considering the climate we live in; nobody here has issues with too much humidity, it's the opposite, considering we spend 1/2 our winters in -30 degrees Celsius. We all have humidifiers installed in our homes to keep our floors from gapping too bad in the winter!

I talked with the builders site assistant today, and asked if he has seen this in any of the other houses in the neighborhood that were completed around the same time as ours, or since; and he said he hasn't.

Will this kind of tenting damage the actual floor boards? Is the integrity of the finish and wood destroyed from the extra stress on the boards when they are tented and then walked on all day?

This post was edited by CLJP on Fri, Jul 5, 13 at 2:11

I thought hardwood had to be installed on plywood & not OSB.

It sure does sound like your floor was skip nailed. A professional, or even yourself, with spherical rare earth magnets would be able to determine the nailing schedule that was used. Your description of the pattern of tenting indicates that skip nailing may be the root cause.