My guess is the blue border looks like the post is pending for approval.
If that's the case, then it should be tagged with blue border instead. Sometime ago, they stopped allowing posts in that pool with colored borders since it was polluting the results. I'm gonna go ahead and remove it from that pool for now.
No worries.. for future reference, it never hurts to ask for a second opinion via comment or mention your reason for adding a post to a pool, especially for a pool like "misleading thumbnails". It even mentions that in the pool description -> pool #1229.