Nobody can know since you have not provided any system info. This simply looks like the program is picking the wrong icon version based on your screen resolution. You know, that High-DPI displays thing. If that's the case, then adjusting your screen resolution and DPI setting might fix it.
I'm sorry. Yeah, i'm on one of those High-DPI display thing.
I am on a 27" one year old iMac with OS X 10.9.4 installed.
Adjusting the screen resolution didn't work.
Any other ideas?