For context I'm 19NB, turning 20.
Growing up, my cycles were always nearly predictable (with the exception of my period sometimes coming 1-2 days early or rarely a day later.) However, during my last period, it actually arrived 3 days earlier than expected. And not only was it earlier, but it was also WAY lighter and less painful than my other periods. Hell, I didn't even know that I had started until I went to the bathroom and found little spots of blood in my underwear.
The rest of that period was pretty much lighter bleeding and relatively mild (yet annoying) cramps. My periods have calmed down over the years but they have never been light and they are typically more painful.
Not only that, but yesterday, I was spotting a small amount of brown blood! It only last for that day and I haven't been seeing anymore blood since then. I find this strange because I have never spotted before my period before...and I wasn't cramping or showing any other PMS symptoms that day either. My next period is also nearly a week away, too.
To be fair, I'm not really complaining about having lighter and painless periods (minus the spotting), but are any of these changes any cause for concern? I feel healthy, obviously not pregnant, and I can't think of any major changes to my lifestyle that would cause a sudden change.