I finally got around to this and called the guys at superbrightleds. They informed me that since the turn indicator (in the speedo) is a single bulb that flashes irrespective of the directional flasher, the opposite side is going to flash. They also told me that this is a common issue and is resolved by using one of these: http://www.cruisercustomizing.com/kuryakyn-diode-kit-for-metric-bikes-each/part/KY-4709I am going to give this a try. Has someone else had this issue.
...My tail/brake LED is an 1157 base with 24 LEDs. I would have perferred to use a red bulb but need white for the license plate illumination.