Well, there are several options here. The first option is that you changed the rhythm of your sleep and started to enter the active phase just before waking up, which allows you to remember most of what happened. The other option is that you started to subconsciously analyze every time you dreamed after waking up. This always helps people remember about 15% of the information they dreamed about. And if you write it down, you may even encounter after some time that you are dreaming a continuation of what you dreamed two or three weeks ago. Personally, this happened to me.