2001 GMC Sierra Left rear wheel

I got stuck one day and it seems that when the right rear wheel spins a little and then i come to a stop the left rear wheel seems to get stuck like it is jammed, But once I get going it is fine. But I did back up one day after it happene and I heard a little noise from it.I want to know if you think it is it the slip posse trying to engage and should I BE WORRIED. Do you think there could be something brokrn inside the rearend, I never here any noise from it after it happens.

Kevin