When I shifted it into 4x4 I was at a dead stop

 

Sounds like it didnt engage 4x4 all the way and then you started spinning tire(s) then it slammed into 4x4. To make sure you get full engagement of 4x4, I would roll in a straight line for 10-20ft.

 

If you are at a dead stop, put your foot on the brake, put it in neutral, and shift to 4 LO. When you are out of what you are in, stop and put it back in 2WD.

 

That's what happened. It is always better to engage 4WD when you are coasting (wheels spinning and no torque on the drivetrain). I've done the same thing. As long as it still works no worries.

It is also good to back up after disengaging 4WD.

 

You can engage 4x4 on a dry road!! the only time you will have an issue is if you make a turn while on the dry road. These things arent made of glass.