Service 4wd Message

[05SBZ71]

My 2005 Silverado is about to surpass the 48,000 mile mark and recently began displaying a 'Service 4WD' message. Is this more of a scheduled maintanance message or a more serious matter? I have roughly 700 miles to go before my next oil change, is it wise to wait until then to have this issue looked at?

 

Today, when leaving work the truck seemed extremely sluggish, almost if somthing in the drivetrain had seized up. I quickly realized that the truck had shifted into 4WD low. I disengaged the 4WD and continued on my way home with no problems. I feel fairly confident that I did not press the 4WD low button by mistake, instead I think for some strange reason it engaged itself.

 

Any insight would be appreciated. Thank you.