I wouldn't expect an uncomfortable seam there, but it's certainly a possibility. My guess is a slight mismatch in the two halves of the plastic mold. If the vehicle is still under original owner warranty take it back. 1) that provides feedback to the manufacturing folks that they can certainly make improvements. 2) it fixes the issue for you. Do note, when plastic parts are molded, the plastic is injected at a pretty high pressure. It's possible to get a sharp edge at the die parting line. Normally I'd expect the manufacturing folks to keep a watch for this die wear from creating a problem, but mistakes are possible.
If we're talking simple discomfort, it's totally okay to CAREFULLY file / sand down the offending sharp edge. My guess it thats injection molded ABS plastic, with the part molded in color. (There is a risk that it's a black plastic part, then painted gray, but I doubt it. Why is that a risk? Why you'd see black in the hand filed area, not the pretty-and-consistent-with-the-rest-of-the-interior gray) Do note, when plastic is molded there is a strong skin formed in the part. When you file it, or sand it you will lose some strength to the part, because you are removing the strong skin/surface. In this case I doubt it makes a difference; that part appears to be totally cosmetic in that area.
An other alternative it to add a piece of sticky back adhesive / high density foam tape or sticky back adhesive felt (velvet) tape to preclude the sharp edge from rubbing you leg.
If it were it my car, I'd first mark the sharp area with a piece of masking tape, then I'd remove the part from the vehicle; do the work CAREFULLY on the workbench, using a half round file to just remove the sharp edge of the part. I'd only take off a millimeter or two, no more than that. You just want to knock down the sharp edge.