do i need to replace head bolts when replacing heads?

I recently replaced the heads and got a valve job on my 1990 plymouth laser. It ran great for aprox. 1 week. then all of a sudden white smaoke come from everywher, under hood, out the exaust. tons of white smoke. so I immeadtly stop driving, I'm sure I dodn not drive it far enought o get it hot. anyway the question I am asking is I have heard the when replcaing the head gasket, replacing the head bolts is a good idea, because they get streched out over the years, is that true? should I replace them.The car is 15 years old after all but, it will be well over $100 to do so. Do you think this is my problem? the car ran fine for a week before it started doing this> please please help///