Is there a red variant to the 2x1 palisade brick (30136)? I looked at bricklink but couldn't find anything. Known colors don't include red or any similar shades, but I feel as if I've seen the red bricks before.
As of this moment, officially - no. The ones available for sale are, most likely, test runs that made their way from LEGO factory since none of them have been included in any of sets. Red is known to be common color for running tests with injection moulding. Quite a few other test parts in Red (the color that hasn't been used by those particular parts in any of released sets) have made their way from factory and have been offered for sale.