2004 620ie Top speed 90mph???

Hi everyone, I am new to the forum and have little experience with Monsters so hope someone out there can help.

My girlfriend has recently purchased a 2004 Monster 620ie and loves it. It seems to ride perfectly until it gets to around 80-90 mph at which it gives no more. It will comfortable get to this speed in 3rd gear yet even when you change up the speed will not increase past this, the revs just reduce as you would expect.

As mentioned the bike is new to us so it could probably do with a full Ducati service but i was wondering if there is anything obvious I am missing. I have had a search online and it doesn't appear to be a common problem (or one i could find any info on). The previous owner was a woman who was nervous rider so is it possible a limiter or something has been placed on the bike?

Any help or suggestions would be greatly appreciated.

Regards