My 2014 Siverado 5.3L recently started this noise upon startup that lasts only a sec or 2. Hard to describe, like a quick metal rubbins sound. It quits and runs normal. It had a canister vent solenoid put on recently and an oil change.
any ideas

 

I doubt this has anything to do with your carbon cannister. If this was not an issue before the oil change, I'd be looking at that as a possible problem. Lots of oil change places use cheap bulk oil and cheesy oil filters I wouldnt put on a lawn mower.