Driver Seat , Transmission Roughness

I bought my Honda Accord 2004 2 dr. 3 months ago. Car is still in
brake in period, about 3000 miles. Whenever I make turn my seat seams
to move a little to the sides – does anyone have such problem? Other
thing is my transmission is rough right at the morning, after night or
after about 8 hours of not driving. Roughness lasts only for about 5
minutes than gear shifting is normal. I took car to Honda dealer,
they could not find anything wrong with transmission. Friend of mine
has the same car, I took it for a test drive at the morning and I did
not see any roughness. Looks like it could be temperature related
problem, winter is coming and I it can get cold in Chicago. Any
thought on both of the issues?
Thanks a lot.
TD