If you take a look in your theme’s style.css file around line 1543 you’ll see this –
.sidebar .featuredpage .page img,
.sidebar .featuredpost .post img {
margin: 0 0 15px;
width: 96%;
}
You can change the width to “auto” and it will show the regular size of the image.
If you’re not using a program that shows the line numbers of your css, then just hit command + f or ctrl + f on your keyboard and search for the terms that way as a shortcut.
There is going to be a major update released for this theme (and all themes) by Wes which means you won’t have this type of issue again.