It means you need to get a new hobby... seriously, why do you care if it changes nothing what so ever. In order to fix this, you should try not checking your battery percentage every 2 minutes. On the upside, this will probably give you another half hour of battery life as well.(damn a change of attitude would fix like 90% of problems on this site)
On a more serious note, it's likely just because your phone doesn't keep charging when it hits full charge, it stops charging in order to not kill your battery, and lets it drain to like 90% at which point it will charge back up to 100%, so it may be at any point in between when you disconnect it. Even if it is truly at 100% when you disconnect the charger, the measurements may not be completely accurate when approaching 100%, so it is likely, that could make it drop faster at first. You need to do nothing in order to fix this, seriously don't mess with it.