Mumsnet hasn't checked the qualifications of anyone posting here. If you have medical concerns, please seek medical attention; if you think your problem could be acute, do so immediately. Even qualified doctors can't diagnose over the internet, so do bear that in mind when seeking or giving advice.
The past few months, my periods have been weird. 2 months ago, I had a crazy heavy one, followed by a normal one 25 days later and now on again on day 21. I'm 31, not on any hormonal contraceptives, always been pretty average/regular. I temp and had a big temp drop today so definitely my period but should I be concerned it's so early? I've tracked religiously for 2.5 years and cycles have always been 23-27 days but 90% 25 days.
If it's just one off I wouldn't worry. Its only slightly shorter than your shortest so far, it's not really beyond the realms of normal. If you suddenly had like a few in a row then maybe see the GP but otherwise wouldn't worry. Bodies do random things all the time.
Thanks @MeadowHay. Bloody health anxiety reigning again.