The 5.7-litre engine in my 2001 Holden Monaro was 'reconditioned' at about 55,000 km and paid for by Holden for what I assume was piston slap. It has now done 145,000 km and there is certainly a noticeable noise on first starting the engine from cold that gradually disappears. Would this be piston slap? Does Holden still own a responsibility for this?
You'd need to have an experienced mechanic listen to the noise to determine if it's piston slap or not. The LS1 certainly rattled on cold starts due to piston slap, and it used oil, they were the giveaways to a problem with the engine. Yours could have some piston slap, but your description suggests it's not serious, and certainly if the engine isn't oil to any degree I wouldn't be concerned. The noise could also be a worn lifter, that's why you need someone with experience to listen to it.