2002 Chevy Suburban Top End Knock

Engine Mechanical problem
2002 Chevy Suburban V8 Four Wheel Drive Automatic 53K miles

I’ve owned a 2002 Suburban LT 5.3L for a year now, its done 53,000 miles. Every morning at start up there’s a top end knock which gradually fades away after about 30 seconds, if I didn’t know better I say it was an empty hydraulic lifter which pumps up. However a pal tells me he heard it’s something to do with piston knock. The question is: Should I be worried and get something done about it?
Best Regards
Gus UK