That's odd. The theme has always displayed full content instead of a excerpt on the blog page. You'll see the except on archive pages.
There's two possible solutions:
1) Use the
<!--more--> tag in your posts. It will create a "Continue Reading" link and separate the content. See http://en.support.wordpress.com/splitting-content/more-tag/
On the downside, you'll have to edit your old posts so perhaps solution two is better for you.
2) Create a child theme (https://github.com/jayj/Cakifo/wiki/Child-themes) and copy the content.php file from the parent theme over in your new child theme. Find line 78 and change it to
<?php the_excerpt(); ?>.
Hope that helps you. If not, feel free to write again. If you have any questions beside this one I recommend you sign-up for theme support on Theme Hybrid.