2006 Colorado, RWD, 2.8L i4, Manual Transmission, 169k miles. I purchased the vehicle from a private seller, since purchasing I have done alot of maintenance, much of it that isn't related to my question, however, I have...

• Installed new oil pressure sensor,
• Installed new O2 Sensors,
• Cleaned the throttle body
• Run several seafoam treatments through engine block and fuel system
• Replaced the ignition coils and spark plugs
• Changed the oil and oil filter. 
• I replaced the injectors. 
• I took the resonator box off and have run a straight pipe from the air intake to the throttle body
• I installed an oil catch can, although I'm not certain I really needed one. 

So there is a tick coming from the valve train. When I listen to the engine with my stethoscope it is loudest under ignition coil number 1. I don't hear any other noteworthy noises coming from other parts of the engine. The engine runs rather smoothly. 

In march I had the intake manifold off so I could clean carbon build up from the intake so I figured I'd take the valve cover off and clean it and check out the condition of the valve train. I found marks on the rollers, I ran my finger nails over them and they aren't deep gouges, just marks. 

I also noticed some wear on the camshaft lobes, the wear on the lobes is smooth rather than rough. 

I've attached some pictures of the camshafts and rollers. 

Pictures of Camshaft and rollers