You should be able to check the coolant level through the expansion tank unless the tank is discolored and/or there is no antifreeze in it. Did you have the A/C on for awhile right before you shut it down? Sometimes that can be the sound of a gurgling noise- something about refrigerants and phase transition and whatnot.
If the coolant level is fine and the temperature gauge rises normally to operating temperature (12 o'clock) and stays there, it's probably OK for the time being. However, if it's never had any work done to the cooling system and it has over 100-120k miles, it's probably time to start thinking about addressing that before it leaves you stranded somewhere.
