Ok, about a month ago I purchased a 02 Volvo S80 T-6. I love the thing, but the only problem I keep having has to do with my brakes.

My brake peddle nearly goes to the floor before my brakes grab, as if there was no pressure behind it. I have found if i tap the brakes lightly before begin to brake the brakes are right there, as if they had to build up pressure before I brake. One time, when my brakes nearly when to the floor I had a message pop up saying "Anti-Skid Service Required". The message went away once I turned off and turned back on the car. The message never comes on when I tap the brakes first to build up pressure. Please Help, Could this be as simple as air in the brake system (By the way, Brake fluid is full, and no fluid loss what so ever) or could this be something more serious?