tumblr_client: Unable to post images: HTTP 401 Unauthorized

I am unable to post images using the client, but am able to post text.

Using the gem entirely outside of the context of my Rails application, I made many successful text posts, i.e.:

client.text("mygreatblog.tumblr.com", {title: "test", body: "test even more"})
=> {"id"=>62354560747}

but when I attempt to make a photo post which I’ve been doing successfully for months, I get the following:

client.photo("mygreatblog.tumblr.com", { source: ["http://static.ddmcdn.com/gif/great-white-shark-1.jpg"], state: "publish"})
=> {"status"=>401, "msg"=>"Not Authorized"}

I’ve tried this with a few other blogs/oauth tokens. This one was just authorized/generated today (fake blog url). Any ideas?