This is a common symptom of peri menopause. Periods can become close together or far apart. You can miss them for months but get all of the symptoms of a period being imminent but then nothing happens. Long periods. Short periods. Spotting are all normal. It's caused by hormone levels fluctuating so in basic terms the hormone level tells the womb to bleed then the level changes and the bleeding stops and so on.
Try not to worry. You can go almost a year without periods only for them to start again. The one time you do need to be concerned is if you have bleeding after sex or if you have bleeding more than a year after your last period. Both of these need to be reported to your GP.
Hope that helps.
Taz x