I've never used stix but as I understand them, they only measure acetoacetate and not BHB which is the primary product of ketosis, and ACAC levels are at their highest during the adjustment period into ketosis, not during ketosis itself. So it sounds possibly like you've been able to adjust into ketosis more quickly than most (took me a few weeks, for example).

I've never been into any sort of lengthy fasting either. In fact I lost all my weight while still eating 3 times a day. It was only this year that I managed to cut back to twice a day (16:8), and even now I've reverted back to 3 times/day while I recover from surgery.

So no, I wouldn't be concerned at all. Listen to your body: eat when you're hungry, don't when you're not. It's pretty simple.