Question about the route directions...

If I'm in the Text screen, with the list of text directions up, and I'm cycling backwards and forwards through the list with the knob... Sometimes the wording of the directions will change as I cycle through the list. For instance, one particular line will flash between "bear right on xxx" and "continue on xxx", as if the software can't make up its mind which of the two turn instructions to give me.

Is this by design, and if so, why?