What is Android upgrading here?

[Natey2]

My tablet rebooted unexpectedly during a AnTuTu benchmark, and I saw this screen during my device startup:

I'm still at v4.0.3, so what did it upgrade?

 

[Astrix]

Optimization of application.
Try couple of reboot after the upgrade for it to settle down.

 

[leeshor]

4.03 is the version of ICS but you also get new builds and that's what happens with a new build update but you will still be at 4.03. The new builds may had a few features and hopefully fix some bugs.

 

[Frederuco]

Any time the caches get fully cleared, it shows this. Not sure why it happened to you, but it is nothing to worry about IMO.