Is my bike getting good MPG

[packie]

Ive got the 1999 model and yes i ride mainly in town and on short journeys 

Then you are getting pretty reasonable fuel consumption. I reckon your are getting about 43-45mpg for a lot of low gear riding and stop starting. That would bump up tp 50mpg+ if you were doing longer trips which is about the norm. The reason you were alarmed was some folks said they got 200 miles to the warning light, but you forget that these dudes have nearly an extra gallon and could be talking about motorway riding too.