GSTR 9 ITC mismatch

Mr.A has received a purchase bill in the month of February 2018 from Mr.B of Rs.20000+3600 GST and Mr.A make the full payment to the Mr.B through cheque during F.Y 2017-2018.In that case Mr. A take the ITC of Rs.3600/- but the details was not reflected in GST 2A .My query is can Mr.A will revert the ITC in GST9 or he is still eligible to take the ITC because in GSTR 9 excess ITC was reflected.