TMP 36 temperature read rises quickly to approx 45°C and doesn't go down again

Being new, I'm working out the exercises in the book "arduino projects book".

On project 03, the temperature reads approx. 20°C @ 0.71V.

When I put my finger nearby or on the sensor, the temperature rises and after +2°C , the blue LED goes on.

But then the temperature rises quickly to 45°C, in no time, the other two LED's lighten up. Not being ill, this is pretty weird. And the temperature does not fall down again. It stays at 45°C.

Anyone tips on what I could / should do?

The sketch is exactly as in the book, the setup on the board is ok. Sensor is not turned around.
Should I calibrate the sensor? And how would that work. I found calibration with a light sensor and applied it, but no idea whether this worked.

Thanks
Stijn

Schematics? Code?

Oh well, why don't you start by reading the How To Use This Forum sticky and follow the instructions, then I'm sure we can say a lot more about your problem.