Confusing reading from a PIR sensor?

Hey, trying to make a bot follow my hand, Voltage increases when heat source passed in front of it,

But when I touch/hold the PIR, voltage goes way up as expected, but then drops down, to even lower then room temp readings?

wth? no way it somehow detects Change over time right?

(Please and thank you)

I believe you are seeing the PIR calibrate itself to it's surroundings. That's how they work, they calibrate to what they see then "trip" when they detect heat movement. At least that's what I thought.