When you first obtained Title Insurance for your property, you were the named insured and the name on title. Once you transfer title to the Trust, there is a new title-holder, i.e., the Trust. Some title policies do not automatically provide coverage for trustees of their trusts under the Continuation of Coverage provisions of the policy. Newer policies have been including such coverage, but older ones do not.
It is best to check your policy to see whether it provides such coverage already. If it does not, or you are not certain, call your title company to ask them. If they inform you that coverage does not extend to you as trustee of your trust, purchase the Endorsement for a nominal fee and you will be covered.