There are "grades" of Bruce/Armstrong "manufacturered" natural hardwood flooring.
Low grade or "tavern-grade" grades usually denotes excessive graining differential, lots of knots, with some surface inconsitencies, and minor manufacturing inconsistencies.
It is unusual to end-cut field pieces, but not unheard of. Many times you do what you have to do and conserve materials to make the job look good while ensuring there is enough material to do the job, which is my guess in why they were end cutting field pieces, if some of the ends were out of square and enough of them were out of square to have a shortage if they didnt end cut them onsite during the install. The installer should be commended for their craftsmanship in that reguard instead of using the pieces as is allowing gaps in the ends of the field pieces.
However, uneven cuts at stair nosing are not proper instalaltion techniques and I would consider that installer error.
Gapping is not proper if at the install time and would fall under installer error.
If the gaps appeared over time, then it sounds like one of two things has occurred:
1. the wood was not hunidity and temperature (climate) acclimated prior to the installation, or if it was, it was not acclimated for long enough.
2. ... OR ... there has been a vast climatic change in temp/humidity in your home since the install, enough so that either the lack of acclimation and/or the climate changes has caused the wood to shrink up, IF it was no gapped at the time of the install.
Either way your installation area should have been tested with a humidity meter and the wood itself should have been tested with a humidity meter the day of the install by the installation crew or a company representative to insure it was withing Bruce/Armstrong installation specs and requirements BEFORE it was installed.
To view the installation requirements and considerations for Bruce/Armstrong 3/4" Natural Hardwood Strip/Plank Flooring to see if the were things the installer didnt do properly or did improperly, please click here: http://www.bruce.com/content2/resam/files/18898.pdf
Wood is almost like a living entity.
It will grow and shink in non-climate controlled buildings.
It is the nature of the product and even more so in natural solid wood varieties such as with Bruce Armstrongs 3/4" natural solid wood products.
It's hard to tell what caused the gapping exactly.
I am only listing the possibilities.
Bruce/Armstrong is a very good company with a fantastic technical services and customer services departments and they take care of their customers.
I would talk to home depot and get them out there to look at it, and if that doesnt suit you, then contact Bruce/Armstrong directly.
You can contact Bruce/Armstrong Technical Services Cstomer Relation Department in 3 ways.
9:00 am - 4:30 pm ET
Armstrong World Industries, Inc.
Customer Relations and Technical Services
P.O. Box 3001
Lancaster, PA 17604
good luck and I hope you get the situation rectified to your satisfaction.
There are two ways to do any job. The right way and the wrong way. Do it right everytime.