Do women's vaginal lubrication levels change with age?

It is very common to see lubrication happen quickly in a woman when she is young (teens to early 20s), in the early stages of a relationship, or when very intensely excited by something new. But the brain being what it is, a person becomes accustomed to a certain set of stimuli -- even if those stimuli are exciting. Because of this, the lubrication effect happens more slowly. It's like the brain is saying "Yeah I like this, but I already know what's coming." In fact, it is not uncommon for women to need some stimulation for 5, 10, even 15 minutes or more before they can experience this lubrication. This does not mean that a woman in not physical or emotionally excited.  Actually, a woman may very easily reach orgasm without having natural lubrication and she will find that she becomes very wet after the orgasm. There is also a great deal of variation between women and the rate and amount that they produce natural lubrication, just as there is great variation in men and their production of pre-cum.