The first time it happened, it could be an outlier. It could be a bad apple. It could be a data error.
The second time it happened, you began to wonder, but there wasn’t yet a cause for alarm. Maybe you’re getting through the early stage jitters.
Once you start seeing the same data coming up again, and again, you have a trend.
Trends don’t lie, because no matter what the cause of the trend and whether or not you think it’s valid, it’s still a trend, and everyone can see it. So, you better take it seriously, before it moves from trend to something more permanent that you can no longer easily correct.