2day AF but unusual

Has anyone every experienced a short 2 day AF having usually had a 4 day one?

I've normally had a 4 day af when being on and off birth control. Came off birth control in the summer after a number of years and af adjusted after about 2 months. They've still then remained as 4 days usually with 2-3 v.heavy days then a medium day before then having spotting on day 5. But this month it was 2 days (only one heavy day) then a medium/light and then no spotting and my af was 6-7 days early.

Is it just my periods adjusting or could it be something else? I will add that my CD was 23 this month and had af 7dpo and 27-28 last month.