Is a major oil leak a major problem? Well, any oil leak on a new car is absolutely unacceptable, and if a leak is “major”, it could cause you to operate the vehicle while the engine is dangerously low on oil. Of course, you did not define the oil leak in terms of quantity or how often you have to add oil, but, in general, an oil leak of “major” proportions could cause you to operate the vehicle with insufficient oil–and that is indeed a major problem.
So–as was said, you should immediately avail yourself of the protection of the warranty with which the car came. Begin by reading the terms of the various warranties (there are several, including the powertrain warranty, the bumper-to-bumper warranty, the emissions warranty, the seatbelt warranty, the rust-through warranty, and perhaps one or two others) and familiarizing yourself with their terms.
Also, read the details on the Lemon Law in your state, just in case the dealer does not rectify the problem on the first try. Make sure that every repair attempt is documented and that you have a copy of the documentation in case you have to invoke the Lemon Law.
Good luck!