I was having the same doubt after creating my first post here on steemit.com. I went ahead and right clicked and opened the image in new tab to see the URL. You know what? it is coming from amazon's S3 storage. Let's assume that what you call this IPFS but thats not permanent and even considering that a distributed storage, it is controlled by a single entity. If anyone can put a little more light on that, it will be great. here is what my link of the image looks like.

and if by any chance you are interested in reading the post here is the link for that.