2001 3.2 Rodeo tap on start

My 100K engine taps on start-up--most noticable in the morning after sitting overnight. Sounds like a hydraulic lifter noise and it goes away after a few minutes driving and warmed up once. Don't notice it later in the day even if it's been sitting for several hours. Not severe, but it doesn't sound right.

I use synthetic 10-30 oil and a Fram Extra Guard filter on it with about 1,500 miles since last oil change. Had the timing belt and water pump changed about 6 months ago, I noticed this tapping this noise fairly recently. Any thoughts? Sticking valve? Wrong brand of oil filter?

Otherwise the engine runs smoothly and without a noticable changes.

This engine doesn't have hydraulic lifters. The problem could be worn cam follower shims. The noise is probably going away after oil starts washing over the cam and followers.