Not necessarily so. A head gasket starting to go can result insome consumption of coolant in the combustion process before it starts to contaminate the oil. Early signs are usually air bubbles in the overflow bottle moderate rpm, white smoke from the exhaust, a sweet smell to the exhaust, and plugs that look as though they have been steam cleaned.
What is encouraging is that fact that the coolant is going away quickly. this, to me, would indicate a lilelihood that the problem is in the cooling system. Either a hose, water pump, radiator, etc. Keep an eagle eye out and it will show up.
you're right Daryl about what you mentioned above.
one of things done on my 80 for the cooling system was to put this thingy on the radiator which pumps air/pressure on to the radiator hoses, etc, etc. usually this way you're able to find the water leak/s if it's a hose, but more than likely consumption of water, white smoke on the exhaust and the smell of other then gas, it's the head gasket.