It is indeed a kernel panic, the default behaviour is to display this screen rather than printing anything useful unfortunately.
If there's nothing in the system logs in console, then you can try booting your Mac in verbose mode. Hold Cmd + V while powering it on, you'll know when you get it right when loads of text gets written to screen instead of the normal spinning indicator.
Verbose mode causes kernel panics to log information to the screen rather than just showing the "you need to restart your computer" instruction. If you get another panic this should at least give you more specific details about the problem.
Apple's official troubleshooting guidelines recommend a safe boot and then a reboot. That support page also includes advanced troubleshooting information such as the location of the panic logs.