Well, the earlier kernel panic might have resulted from a transient problem affecting hardware. Not necessarily the Mac, maybe a peripheral.
When it starts with neither a panic nor a hang and automatically offers Disk Utility and so on: that behaviour may be expected when there is, in NVRAM, a setting that's associated with unfinished installation of the operating system.
If you now reset NVRAM you'll clear not only that setting, but also the settings associated with verbosity (the white texts on black background) and additional information within kernel panics. Go for that reset, then Command-R to start Recovery OS and use Disk Utility to verify things.