It's not anything to worry about, it just means you are not currently voting with all of your stake. Anyone that owns shares in a DPOS DAC can vote on the delegates that they trust to sign the blocks and ensure the DAC remains decentralized. If you wish to use all of your votes you need to "thumbs up" 101 delegates and then "update vote" in the vote tab which costs 0.5 BTSX in fees.