As mentioned by LW001 this could have been earned over a series of months, for example you earned $3 in January and then the rest in Feb, as such you would of only have been paid for January's payment so far in line with our payment schedule.
January's monetized views are paid out at the end of March (Mar 31st)
February's monetized views are paid out at the end of April (Apr 30th)
March' monetized views are paid out at the end of May (May 31st)
April's monetized views are paid out at the end of (June 30th)
May's monetized views are paid out at the end of July (July 31st)
June's monetized views are paid out at the end of August (August 31st)
July's monetized views are paid out at the end of September (September 30th)
August's monetized views are paid out at the end of October (October 31st)
September's monetized views are paid out at the end of November (November 30th)
October's monetized views are paid out at the end of December (December 31st)
November's monetized views are paid out at the end of January (January 31st)
December's monetized views are paid out at the end of February (Feb 28th/Feb 29th)