The VFR800 service interval is 4000 miles. The handbook is clear that the runner has 8000 mile service intervals.
If the dealer is telling you you need a 4000 mile service look for another dealer as they seem to be trying to con you into extra services that are not needed to maintain warranty.
However, always good to have a regular check around the bike, you can do this yourself, for things like brake pads which can go from loads left to need to change now in 4000 miles. Chain and tyre check should be done regularly, not waiting for service.
Having said all that there is some opinion that the V-tec engine really does like 4000 mile oil changes, again a really simples job that you can do yourself very easily.