Our hardwood floor is not installed straight. When we questioned our installer he claimed it wasn’t his fault, the problem is our walls are not straight. He claimed that the defect is within code for hardwood floor installation and he is not responsible. My husband checked the floor with a T-square and thinks that the problem is the installer did not snap his caulk line correctly. We are probably the only people who will notice this defect, but will this faulty installation cause problems in the future? My husband wants to take up the floor and install it correctly himself. Is it worth it to do this? Also the floor was installed when humidity was approximately 25, the manufacturer recommends a humidity of approximately 45. Will this cause any problems?

Do you notice it everywhere the products runs parallel to a wall, or in just one area? If it is just one wall, then perhaps the wall is out of square. I usually start off the longest wall, snap some lines, check to see if any out of square areas occur, correct if possible, and if not, notify the customer before I start, so we don't have the situation that you find yourself in now.
You could contact a inspector to look at the floor, and use his info to seek further remedy.

Thanks for the reply SK. We noticed the problem everywhere. Not only against the walls but especially where the hardwood ends and our stairs down to the front door begin. Also what kind of inspector should I contact to inspect the floor.

If you are the only ones who would notice it, then it must not be too badly "out of square". The installer could be partially correct. Is the wood straight on the exterior wall? If so, the interior wall may be out of square.
The installer is required to install one wall straight, which is usually the exterior wall(s) as the exterior walls are most likely the straight/square walls.
If the installation is "slightly out of square", the cure may be worst than the disease and more costly than you wish to participate in.
Ray

I have had to make an installation "cheat" before.

The wall was out 3½ from the outside wall 28 feet across the room and grand entryway, like they marked the bottom plate wrong, when popping lines on the slab for framing the home.

Good thing I caught it! As it would have been very crooked, right in the grand entryway, as you walk in the door, if I had just started off the outside wall.

It was cocked along the outside wall, but not much once I cheated a little, after showing and explaining to the homeowner, and using a little filler on the gaps, she was well aware would be there. She loved it, but only because I kept her informed of all concerns as they arised through the entire job.

Reason # 204 to square off of the plywood and not the walls.

Chuck, please explain "square off the plywood". What do u do with concrete sub-floors?