Sometimes you may find some extra space added above the slim optin form, making it not so slim ;)

To fix this, first go to your Divi Library and in the Super Slim Optin layout, check you only have the Bloom shortcode and no extra <p> tags are shown, if they are remove them.

Clear your caches and check to see if the issue is fixed. If it is not, then add the following to your stylesheet or Divi theme options:

/*Added 20/02/18*/
.ds-slim-optin-form p {
    padding-bottom: 0;

Applies to V1.4, fixed in V1.5