Well that would depend on the intent behind the statement.
Is Pinocchio making a factual statement, or is it something he knows through some predetermined means?
If he's making a statement he deems to be factual, then his nose shouldn't grow in the first place, because he's under the presumed belief that his nose is about to grow - which is in fact not factual. It doesn't make it a lie, it just means that he made an incorrect statement. If you believe a chair is blue, when it is in fact white, does it make it a lie, or does it just mean that you cannot distinguish colors correctly?
If he's making a predetermined statement, that his nose it
about to grow and it doesn't, then won't his nose grow eventually? About doesn't really specify time does it? It's not exactly quantifiable. If I say that I'm about to make some breakfast, only I can know quantifiably what I mean by "about". If about to me is 5 mins from now, and I don't make breakfast, then I've stated a lie and my nose will grow.
