it is not always the case of head gasket going if you do not do long trips only short ones this can also cause it. Hope this helps
well my wife's car did exactly that she did about 2 and a half miles a day going to work and back but no bus route, now and again we take it on a long run to really get it hot and I check the water every week as that is a must on the 1800 engine
Then it would definitely be ####ed.