Zero Turn Mowers

I purchased my husqvarna mz6128 3 years ago and had multiple problems but love the mower. Just today I went to mow and when I engaged the pto for the blades the blades started very slowly and never reached full speed. I'm assuming the clutch has gone bad but it made no noise's during the previous mow. My question is is this covered under warranty since I purchased the 4 year warranty or is that another one of those items not covered under warranty?