Some people incorrectly think that if an exchange is decentralized that they control their coins. This is not necessarily the case! The simple rule is "your keys, your coins; not your keys, not your coins". I went looking for my EOS private key on Bitshares last winter and discovered that I didn't really have it. Fortunately I rectified that matter before launch. OpenLedger, Rudex, etc may be managing some of your private keys for you.