Intake Manifold Gasket

Recently brought my 99 Grand Am into the dealership for an oil change and we have an apparent oil leak related to the intake manifold gasket. First question: What does the intake manifold gasket have to do with oil? I was under the impression that these two things would be completed unrelated. I hear that this is a common problem on a lot of GM vehicles, so it would be helpful if anyone would have any suggestions on about how to approach this problem. Is it a different problem? Get it fixed at the dealership or elsewhere?

The intake sits on top of the block and runs air into the head/heads oil is getting pumped right under the intake manifold so why oil doesn't flow threw it it is also used to keep the oil from pouring out the top of the engine. Yes this is a very common problem and if not installed correctly and given enough time to set. A vacuum leak will take place but its not a super difficult procedure if you take your time and have a service manual to guide you step by step or any garage should be able to handle this type of job. Good Luck

John