If it happens once in awhile on an irregular basis, it's not a problem - it's a very common peri-menopause thing.
The hormones are fluctuating and an ovary misfires every so often - early or late.
I had this happen to me maybe 2 or 3 times spread out over a year.
I'd have a normal period then have an early one 14 days later (lasting 5 days for me).
I also would skip a month here and there, too.
My periods would be normal, normal, early, normal, normal, late, normal, early, normal, normal, etc randomly all over the place - this went on for years.
Now I'm 51 and to a point where I can sometimes go 50 - 63 days between periods and I'm hoping they stop altogether pretty soon now - they are just a pointless bother.
The only way I can tell if a period is coming is I break out with a blemish or two the day before.
If it happens a lot - every time - you can start to feel anemic pretty quickly.
My friend had this happen - her time between periods shortened till she was almost bleeding continuously.
It turned out to be an early symptom of breast cancer.
They caught it early and she's fine now - been cancer free over 15 years.