I assume when he exits the pits and runs through all the gears, he does this as a precaution to make sure the first time he tries to upshift or downshift at speed he doesn't find a neutral?
Like when Lorenzo never downshifted after a practice launch at Laguna and his launch control never turned off. Then it spit him 10ft in the air when he tried to turn.Love the way the dash was fuzzed out so as not to show speed, etc. Going through the gears may set/reset the computer/quickshifter or it may even be a habit/superstition!!
And yeah, he was just cruising!!