the only time I replace the plug hole gaskets is when I take off a valve cover, but I rarely see them leak on their own, unless they have a 100k miles on them... you might have a distorted tube or the dealer might have used crappy gaskets/ or the wrong kind for your car. There is a thickness difference in the non vtec and the vtec D16 spark plug donut gaskets, so they don't interchange! I would take the car back and have them do it again for free - it shouldn't leak that soon after. You might also just have some residual oil in the holes from the last time the gaskets were changed and they might not be leaking at all. You could buy a can of brake cleaner and spray it down the tubes with the plugs still in place and then blow out all the crap with some compressed air, followed by a paper towel wrapped around a long screwdriver to wipe it nice and clean. good luck!