For all types of dashed lines that have an offset value, a triangle may be noticeable for 'V' shaped segments. The higher the offset value the more noticeable this effect will be. For most small-scale maps this should not be a problem. However, zooming into one of these areas, or printing at a larger scale may make this more evident.
This is a known issue in the drawing algorithm used for offset lines. It is only a display issue and does not reflect the actually geometry of the feature.