Yes, it could possibly be a pre-menopausal thing.
Some women actually go through pre-menopause for many years before going through the actual thing....my mom did.
And it could actually be stress and anxiety, as well.
I'm 35, my tubes are cut and clamped, and that has happened to me a few times over the last couple of years.
Usually when I'm going through high stress situations.
I've even had where I have had my cycle be all over the place and last 10-12 days!
And for forever I've been used to it being very much on time, regular, and lasting about 3-4 days only.
Stress and anxiety can do many things.