Late 2009 iMac running extremely hot after upgrade to Mavericks from Snow Leopard

[OldCorpse]

Late 2009 iMac i7 2.8Ghz 8GB RAM. A couple of hours ago, I upgraded the OS from SL 10.6.8 to Mavericks 10.9.4.

Immediately after the upgrade completed, the iMac was red hot. I repaired permissions and shut it down to let it cool off. I turned it back on after it cooled off and immediately repaired permissions again. Very soon, the iMac was running extremely hot again.

I can feel it very hot to the touch. It's cool in the room, so that's not it (it's evening). According to iStatPro:

HD: 142 F
CPU: 133 F
GPU Diod: 190 F
GPU Heatsink: 181 F
Mem Controller: 130 F
Power Supply 2: 140

Fans: HD 1798 rpm
CPU 2921 rpm

I can hear the fans running full speed.

I'm not running anything special - and remember, it was already extremely hot right after the upgrade, before I even logged in.

I looked at Activity Monitor and I don't see anything special, except for a process called "mdworker" at 30% CPU... could that be responsible? Is it like spotlight or something?

Should I be concerned?

 

[Intell]

mdworker is Spotlight indexing your drive and files. It is normal for it to index the drive when a new version of OS X is installed. It will finish in about an hour or two, depending on how many files you have and what kind they are.

 

[OldCorpse]

Thank you, Intell. Hopefully, it'll cool down after that. Whew!