You will need a few more days or so before you could assume that. They allow a little time for credits from flights on partner airlines to come in before dropping you back from Gold to Silver if you fell short.
Edit: if you get comped they would send you a letter saying so accompanied with your new card. They typically send these out even before the year ends so sometimes you may get a letter but actually qualify after that with flights just before the year ends so it turns out not to be a comp after all.
Were you close to the 600 SCs and was your 3 year average good?