Not funny like in HA HA but funny like in I am WORRIED

Went to Welkom this weekend where we are in the process of renovating a house. All went well and the Patrol worked very hard.
On Sunday morning the Patrol started to idle at 1200RPM. When I engage the clutch and put the car in gear the revs dropped to 600 where she normally idles. This continued the whole day. The EGT was normal, there was no strain on the clutch that I could detect.
We came back to Gauteng last light and the idle stayed at 1200RPM. Stopped in Westonaria where we picked up the children visiting their Grandmother and on leaving her house the Patrol idled at 600RPM. Drove to Alberton, to work this morning and everything is back to normal.
I thought it might be the slave cylinder acting up, low clutch fluid (checked, not that), or a dirty MAF?
The Patrol is due for a service in the next 1000 km.
Thanx