Cute picture, but if you didn't draw this, then who did?
I'm not saying you were intentionally trying to steal this piece and I know you never claimed it as yours, but you really should give credit to the original artist, and maybe a link to the original upload as well.
I'm sorry, but in not crediting the original, you subconsciously did steal this piece. If you don't mention the original artist in the image description, people are going to assume that you drew it yourself, whether you said you did or not.
And generally, it's not really a good idea to upload an artwork that you didn't create in the first place unless you have permission from the original artist. (do you?)
Now, don't take this the wrong way. I'm not pointing fingers or calling you an art thief. Just understand the situation.