Q: One visitor asked, "I installed 3/4 OSB directly over a concrete slab, above grade, with a vapor barrier Rosen paper and Nailed down 3/4 Maple (Canadian!). what problems can I look forward to?"

A: I am not a big fan of installing nail down products on "chip board". I know that some if not all hardwood manufacturers will not warranty one of their floors if it is installed on this product. Problem is, it doesn't hold nails well. Since you have installed this directly on the concrete, which I assume is fairly level, you may not have a problem with boards coming loose.
The bigger concern at this point would be moisture or dampness. If there is any problem with this, you will likely get cupping of the floor boards, with the edges raised higher than the center. Maple is more susceptible to environmental changes than oak, for example. If this happens, it will stretch out the nails a little, then it will likely fluctuate in moisture content, and shrink. Then you could have considerable gapping between boards.
The time to ask the question you asked is before you install the floor, not after.:) However, lets hope there are no moisture issues in your basement and you won't have any problems.