I’m not sure I fully understand what you mean.
Are you pertaining to this post list?
If so, I don’t think it’s necessary. There’s already a title below it. Wouldn’t a duplicate title when you hover the mouse on the image be redundant?
Plus I don’t think it’s necessarily good for SEO as the images already have an alt attribute to describe then and you already have an h3 tag w/ an
itemprop="headline" attribute which is the actual title of the post.
But if you must still do it, you can hook in the post title on the post-image element same way you did the
+ sign on hover and style it with CSS.