When webforms are updated from 7.x-3.x to 7.x-4.x, the option to choose whether to display the webform form in teasers on a node-by-node basis is replaced by relying solely on display modes. This means that the choice can be made for each webform content type, but the choice is the same for all nodes of that type.
Webform, however, continued to display the form in the teaser, regardless of the display setting for the content type's 'Teaser' display mode. Version 7.x-4.5 corrects this. By default, the webform pseudo-field is NOT included in the Teaser display mode, and accordingly will not be displayed, for example, on the default front page.
To restore the pre-7.x-4.5 behavior, visit YOURSITE.com//admin/structure/types/manage/webform/display/teaser and adjust the Webform "field" to be displayed.