read() method of Pin class resets the pin's state?

I did some experiments with setting and reading LEDs using firmware 1v52:

LED1.set()
=undefined
LED1.read()
=true
LED1.read()
=false

The set() method lights up LED1 and the read() returns the right state. In addition, read() switches off the LED, so the next call returns false. Is this expected behaviour?

Best,
Maik