[Lucid:]

whether you get a pearl for a post or not is random. it's not going to be a perfect every-other-post deal.

Think of it this way: Every time you make a post, either a 1 or a 2 is chosen randomly. If it's a 1, you get a pearl. if it's a 2, you don't.
it's possible to have a bunch of non-pearl posts in a row this way through sheer bad luck. But it's also possible to get a bunch of pearl gaining posts in a row as well.