Does leaking coolant into the oil always mean bad head gaskets?

[Chasingstatus]

Hey guys hoping someone out there could point me in the right direction. I did a brief search but everything seems to point in a few different directions.

Backstory and history of the car:
Just bought my girlfriend a 2012 G37x in July. The car currently has 60k miles on it and we bought it with 54k miles. The previous owner mentioned it had over heated and he had 1 of the head gaskets replaced. I was weary of the purchase but we reluctantly went through with the purchase (stupid I know). I've noticed a slight antifreeze smell lately and seen the overflow tank losing coolant. I told her all summer to keep and eye on the temp gauge and she said it never climbed anywhere close to overheating during our ownership. So I did a oil change tonight after seeing a slight milky residue on the bottom of the oil cap, sure enough....it's mixing. She works less than 5 miles from home and seeing as it's winter I see this could cause this milky residue in some cases (it's not bad like pudding caking under the cap and nothing on oil dip stick out of the ordinary, just I figure any residue can't be good). The car doesn't smoke at all and the exhaust doesn't smell sweet. The antifreeze smell comes more from front of the car. I'm hoping maybe there is a issue some of the ogs on here have dealt with before I go and replace these head gaskets. Just between not fully knowing the history of the heads in the past I don't want to deal with this issue down the line. So now I'm worried like maybe he warped a head, or maybe his cheapness got us in the long run from the original over heating issue and only replacing one gasket? Just trying to bounce some ideas and any help is greatly appreciated. I also didn't see anything out of the ordinary leaking from radiator hoses. Could I be over looking something? Maybe water pump or oil gallery gasket(see these are common to fail pre 2013) or something? Idk Ive never personally had to deal with this issue in my experience with two vq35de's or my vq37vhr. So I'm kinda at a loss? Thanks again