I read about cylinder slap from a TSB on some Chevy truck. All I know is that the cylinders are a little small (including rings), and until they warm up, they are actually loose in the chamber. I don't recall what the fix was.
If it is the lifters, maybe they tick because of lack of oil when first starting it up. That's just my guess though. If it were me, and I was concerned about it, I'd just take it some where to be looked at.