I really doubt that there would be an issue. I've seen some kids with massive heads - you could orbit sputnik around them ROFL, but they grow into their heads kwim? Does she look in proportion to you though? If she does then I would say it's fine, she has just had a bit of a growth spurt and her body will catch up. Mind you your MCHN could have measured her head in a slightly different spot to last time too, or the shape of her head could have changed slightly and that could possibly give her a measurement that is vastly different to last time.