I remember a long time ago people pointing out that it was actually posted to Digg first. Imgur's creator says it was posted to multiple services on the same day [1], but that he deleted the original Reddit post. The post saying it was a "gift to Reddit" came a day after the post to Digg failed to gain traction.

[1] https://www.reddit.com/r/IAmA/comments/9tlwi/im_the_imgur_gu...