I don’t know what brand of oil paint you are using, but that is quite normal. It can take weeks for a painting to dry.
As to the highlighting, perhaps your paint was not thin enough. Bobs rule was, a thin paint will stick to a thick paint. So if you have several layers of paint already on your canvas, liquid white, background color, then add trees, then leaves, and then highlights, your paint will need to be thin. Try adding a touch of liquid white, or liquid clear, or a dab of thinner to your color.
i hope that this is helpful,