Please take a look at this cicada photo - http://photo.aseev.com/stock-photo/cicada-exuviae/ - below you will see 5 thumbnails, all of them are squared, except one (a bug on white background).
It is rectangular and it is actually the "medium" size (unlike 4 other thumbnails, which have correct paths to the "thumbnail" size image).
Removing the post and the image from media gallery and recreating the post doesn't help.
The thumbnail image for this file exists in the right directory and it is squared (*-150x150.jpg). In mySQL sizes are defined correctly for the thumbnail, from what I understood.
In media library, each photo has a thumbnail in front of its title, all of them squared except the one I have the problem with.
I upload images programmatically with wp_handle_upload, so maybe there was a mySQL input error.
Don't know where else to look. Anyone else experienced this? Is there a way I can fix it manually in the mySQL db?