Not sure..It would be rare case..
For me, they asked to take the photo again in vfs itself during 1st time submission because the one I carried didn't meet the specifications it seems..
I think some mm differences are acceptable
I've submitted my passport on Feb 16th in vfs, Chennai. It reached Delhi on Feb 19th (after week end) and is in transit to ircc.. Pls let me know once you receive the confirmation of passport stamping. Have you opted premium service in vfs?