Yes the alert is the 'Increased % of fragmented indexes' - even so though, i changed the metric to be collected every 5 mins to intially see if it would change after index rebuild - and it didnt. I think i know why though. I have learned that sometimes after you run a defrag, if the indexes pages are small and over multiple extents then they remain fragmented. Is this correct ?

Even so though i still dont get why the alert showed as downgraded ( so it recognised my good work at defragging the indexes 🙂 ) but never changed from a red 'high' to a blue 'low' alert.