Service 4wd/Stuck in 4Low

[Karensworking]

I have a 2006 GMC Sierra. The service 4wd message came on and at the same time, I got stuck in 4Low. I parked and shut off the engine and upon re-starting, it was fine. It was scarey to get stuck in 4Low being 225 miles from home. The local dealership and my trusted mechanic have not been very helpful (nor economical) in the past in diagnosing or fixing things on the first (2nd, or even 3rd) visit. I would love any info on this topic or any questions I should ask when searching for a new mechanic who can fix things the 1st time. Thank you!