I've got two oil changes and 5,000 miles on mine.
This happened to for the second time yesterday.
I usually start the bike in neutral to let it warm up. Now I hold the clutch in just in case the bike wants to jump gears and lurch forward.
Lol My bike was the king of weird shifting, full synth oil inproved it but... Part of the problem I feel is the Positive Neutral Finder, I've had it jump into gear at a stoplight showing it was in neutral but never during start up...
If first gear isn't fully engaged when you parked it ( you came to a stop in 2nd then down shifted to 1st with the bike standing still, you can actually shift past neutral so the light goes out but not fully engage 1st...
My start-up routine every morning regardless of how I parked, Unlock the steering column press down on the shift lever a couple times ( it wont move down if 1st gear is fully engaged ) then shift up to neutral using even pressure till the the lever stops.
If the shift lever moved down at all during the step above, I will rock the bike forward till it stops and back till it stops while pressing down a few times on the shift lever to lock it in gear, don't hold the clutch - then shift up to neutral using even pressure till the the lever stops.
Feel is your primary weapon and the green light a secondary indicator. good luck drive safe...