Not at all. They are investing their profits into scaling and growing the business.

I don't believe those margins are thin by public company standards. Perhaps we are spoiled by Apple who operates at insane margins?

Huge increases in R&D and marketing expenses, mostly.

They've been reinvesting potential profit into the company in order to grow R&D. (Spend has increased from $57M in FY13 to $141M in FY15.)

Their gross margins are probably what you want to look at instead, since their cost of revenue won't include R&D ($ in 1,000s):

                 FY13     FY14     FY15
  Gross revenue  148,512  215,109  319,521
  Gross profit   115,481  117,123  266,589
  Gross margin   77.7%    54.4%    83.4%

These are very healthy for a software company. They nearly doubled their spend on sales and marketing between FY13 and FY14, which explains the temporary dip in gross margin in FY14.