Invoice was created AFTER the award Close Date (?)

I had the following scenario when running GMS: Generate Draft Invoices for a Range of Awards

  

Inv Date	18-Apr-16
Bill thru	18-Apr-16
Award Start date	10-Aug-09
AwardEnd Date	30-Jun-13
Award Close Date	16-Dec-15
Award Status =	Active

ISSUE: on the April 2016 draft invoice, line items from March and April 2013 expenditures appeared on the draft invoice

HOWEVER, the GMS process was last previously in July 2014.

What circumstances would contribute to these Mar/Apr expenses showing up in draft AR invoice April 2016 and not showing up previously on the July 2014 draft invoice?

Just curious.