Not at all, there is a perfectly reasonable explanation if you fit an exponential growth model to the numbers given.

You see, they must have started with one client, in year one, and thereafter achieved an average growth rate of 151.33% per annum.

My Excel model:

  Year Clients
  1 1
  2 3
  3 6
  4 16
  5 40
  6 100
  7 252
  8 633
  9 1592
  10 4001

In the tenth year, they would have 4001 clients. However, they would have passed 35 clients about five years prior, and therefore the implication is simply that that is the cohort that is completing now and projects last on the order of five years.