Excellent response from Andy. I guess I'll have to age my bottle.

Good morning to you...
And my kindest thanks for your interest and for bringing this question up.
Indeed, I know what you are referring to. But I can and would like to state
hereby officially that the formula of the l'air du desert marcocain, eau de
toilette intense has not changed at all from batch (lot) 1 (first lot) to
lot 9 (last lot on the market so far). With the air du desert marocain being
my best seller I do not have any intension to change a bit.
What you see (darker colour) and smell (softer, more powdery, ambery, more
oriental so to say): This is an aging effect. Like most of my fragrances,
the l'air du desert marocain is built with a lot of natural ingredients.
Before it goes to the shops it is matured for 2 months.
When at the clients, it continues to mature, slowly, but nevertheless you
can see it with the years (darker, slightly orange) , smoother.
The same, by the way, you can observe if you store some essential oils or
absolutes as pure essences. Frankincense or Sandalwood, or Vetiver will
mature over the years, getting smoother, softer, better.
Based on your mentioning the large bottles: I changed the size of my flacons
to an unique flacons in January 2006 (I think). Hence your bottle must have
been more than 3 years old.
So you see: Like a good wine you can enjoy my fragrances after a short
maturation process (2 months) when you get them, but they continue to grow
and get better. This is - of course- a quality you do not get from your
average scent as they are mostly bare of essential oils and absolutes, or
contain much less of them.
I hope you find this answer suitable for your needs.
and send you my best wishes
Andy