You're running into the spam/moderate filter. I don't know for sure how Brian has it set up, but certain behaviors will cause it to trigger - in your case, I suspect it was embedding a graphic with minimal text in the message (I saw it and cleared the moderated flag for the message). If a message triggers the moderate filter it's marked for the moderators to look at - which we do fairly regularly, and posting it a second time will merely cause both to be in the moderate stack.
Most of the time, though, messages go through without hitting it - I'm seeing 1 every couple of days on average.
Returning & editing after finishing my swing through the new messages. Your last couple got caught because of embedded links. That will clear up after you've been here a while -it's there to stop the spam link messages we get a lot of.
Namaste Nick (apologies to bruce who is doing a fine job)
You are targeted by association. Until you stop posting on threads which certain other members post to you will be permanently associated with these members. It is simply a percentage thing. Should you decide to continue posting to these threads with aformentioned implications than the percentage of posts flagged for review will be increased.
However, a donation made in my name to the boards will eliviate some or all of this inconvenience, again depending on the size and speed of said donation a direct association applies.
Lastly ask anyone, the entire above is hokum as mentioning my name won't even get you a good seat in a public stall. We do hope you enjoy your flight and your seat cushion may be used as a flotation device in case of a water landing. (warning this post may contain nuts or nut byproducts as it was processed by machines that process nuts)