In 43 I have started experiencing a slight deviation in dates of my periods. It was stabely fixed to 25 days for years, but for the last 6 months it sometimes happened in 27 days and this month took 30 days. What type of problem I am experiencing and how should I address it?

At your age it is quite possible you are entering perimenopause. You will see periods lengthen and lengthen in days apart until you have none.

Once you do not have a period for an entire year, you are in menopause.

Agreed, or just change in hormone levels as you are getting older. Most women I know start having signs of the change of life, in their mid forties.

or just change in hormone levels as you are getting older.

Um Chuck, that would be what causes perimenopause and menopause.;)