So on my 2009 Xbones I did an engine upgrade, cams and headwork at approximately 15,000 miles. Everything ran great up until about 2 weeks ago with 14,000 miles on the new engine. I lost compression in the front cylinder and after pulling the head, the exhaust valve wasn't seated in the combusion chamber. I took it to an indy that is known for his head work and we took it apart. The exhaust valve was bent with quite a lot of carbon and oil built up around it. After he pulled the valve guides, the exhaust valve guide was cracked. He's thinking the valve seal let oil seep into the valve guide and it was basically cooked inside the valve guide causing the valve to stick and impact the piston, bending the valve. I've never messed with rebuilding heads so I guess I'm asking what would cause the seals and / or guides to fail with only 14k miles on them?