In a way, there is a rush...he is still contracted to Atletico and he skipped a training session which he should have been at. You dont do that unless you are close to a move. Atletico still pays his wages and might fine him for that. If he waited´, there would probably be more training sessions he should be at. And skipping all...i dont really know if thats fine. Do you?
Aguero is in no rush, if he was he would have moved before the Copa America. If somebody comes in for him then he will wait and consider all his offers...if not he'll most likely sign for City, but he won't rush it and I doubt Atletico will fine him if he's in transfer negotiations and if they do his signing on fee will cover it anyway.