Shift cable is going bad on you. By yanking it through all the ranges, you moved it into a part of cable that normallly didn't get used, and had some grease left on it, which lubed up the length that normally sees use (P thru D). As the weather gets colder, it'll bind more you can bet, though. It may get to where you almost can't get it in gear if it's real cold out....
I do the same thing, work it through all the ranges from time to time and it eases up somewhat...Last year I had the cable apart at the adjuster sleeve and force-fed it a little bit of penetrating oil....hasn't been a problem since....