Webmaster tools recently showing a lot of Not Found errors

I have a wordpress blog installed.

My posts url format is domain.com/category/blog-title

Now recently webmaster tools have started showing a lot not found errors and all those errors are in the form

domain.com/upload-date/post-title/imagename

So every not found errors correspond to image name.
I am not sure where i am going wrong as there seems to be no such url when i check the page source from where it is getting linked.

How do i figure this out..