If you’re sitting on some Club Nintendo coins, then you might want to redeem them as coin values are about to change. Come July 1st, many games will be receiving different amounts of coins, which could leave you with far less in the end. However some games are actually getting more coins, so it is evening it’s self out. If you’re still worried, you can find the complete list of changes on the official Club Nintendo site.
While this change is unexpected, July 1st is when Club Nintendo rolls over, so this won’t affect your current standing. Additionally no details were given on the change, but it was most likely due to heavy supports / deal fanatics stocking up on coins to constantly platinum.