Is there any problem if my first service is delayed by 300KM ?

It was supposed to be serviced after 500KM, but mine just reached 800KM and it's been 2 months ( Yes It got delayed in the number of days also) . I am taking it to service centre tmrw, but something I have observed is

a) Hard gear shift especially upshift b) Drop in power, I mean the smoothness went away

Kindly share if anyone has delayed the service?