miritchka,
It was never exact so it was always possible to have been a day off. That being said the calendar isnt perfect since even tekufas Rav Ada (which is used to sync 12 lunar mnths with approximatly with a solar calendar 365 days 5 hours 55 minutes and change) is still slightly longer than the actual solar year of 365 days 5 hours 46 minutes and change. Thus over time the Jewish months are inching slightly forward relative to the Solar months/seasons.
With enough time Pesach will no longer be in chodesh haaviv and will be in the summer then fall then winter no doubt we will once again be mekadersh with reiah upon moshiach’s arrival long before this becomes a problem
Nothing changed in the year 2000 in this regard