Hi Tim,
I never before observed such a behaviour.
The situation:
Last year I kept them in a tank in my newt room, with a lamp.
Then I put them in basement for the winter – only small window, 10 °C.
One week ago they came in a tank in my garden. Here they changed their behaviour complete.
The whole day I could not see them, but in the evening they came out of their hiding place.
Water temperature climbed within one week from 5 to 10 and yesterday up to 17 °C. So I took one of the female out of hiding place and at once it showed such a posture for approximate 10 minutes.
Paul