6000RPM all the time with no activity - restart helped I'm on Mountain Lion and for two days my fan RPM was 6000 and the temperature was 92C. I decided to restart and now it's 3300 RPM at 68C. 

How come? Is this some kind of bug? I remember having problems with high RPM a month or so ago but it was also very hot outside... the problem somehow went away but now it reappeared... since it's also hot outside now I thought that's how it is - but no - there is something wrong and it looks like it's not the dust or hardware problem.. something in the OS is strange.. any ideas?

UPDATE: it's 5500 RPM again - I hate it! :( It was great during the entire day - around 3500 and now for no apparent reason it's 4500-5500... Again no activity on the CPU.. the temperature shows 65C so no idea why the RPM has to be that high.

UPDATE2: back to 3500 RPM all by itself - no restart... Are these fluctuations normal? That's just how it is? I know that being at 6000 RPM constantly was not normal, but what about these spikes to 5000 and back for no apparent reason?
Sounds like the symptoms of a runaway process using a lot of CPU. Sometimes there are also valid reasons. If it reoccurs your best course of action is to open the Activity Monitor, and look for something using a lot of CPU time and try to determine if there is a valid reason for this (an example might be you have added lots of little files that are being indexed by mds (the indexer daemon for Spotlight)