It's possible that the chart you looked at only ranked names with a certain number of 'hits' or babies born with that name. For example, if the cut-off was 50, then the previous years there could have been 49 babies given that name... that would mean only a +1 or -1 drop, but it would be enough to make it drop off the chart. It could have had more or less the same (albeit low) popularity for years, but we'd never know!