No, the first three years of any vehicles life is when the most mileage is clocked up, then it tails off when sold for a newer vehicle. 15000 miles on a transit is nothing, but keep the oil changed regular and all should be well.
I run a 190 tipper, 1998 S plate with 116000 on the clock and is still going strong, i change the oil twice a year and all filters once per year. I know these old work horses go forever and are the prefered choice over the next generation Transit, I cant comment on the new one you drive, but time will only tell on the reliability. :thumbup: