Slightly related anecdote: A number of years back (at least five or six) I noticed that if you made a smart playlist with a time range constraint the "max" time would increase by one second each time you edited/saved the playlist. I sent in a little bug report (through an iTunes feedback form on their website).

Right now I can't check whether the bug still is present in the Mac version, but I can see it still exists in the Windows version.