Tomich Hill aren't a 5 Star winery, and this was the previous ad for the reserve: https://vinomofo.com/wines/white-wine/black-market-deal-chardonnay-2015-120116 (Boutique Producer, Single vineyard etc.)
Edit: though the seem to claim they are a 5 Star winery on their website, and the 2015 Wine Companion has them at 5 Stars (I don't have the 2016 handy - maybe they got downgraded? or maybe the Wine Companion website is out of date)
The price discount matches the previous offer ($45 -> $13.50)
I thought it was Tomich Hill as well, as I would like some more. I was talking with Kate this afternoon and asked her if this chardonnay was one I had ordered before, but she said that it definitely was not. but was talking to Kate this afternoon about something else and she said that it was not. The last listing for the Tomich Hill reserve mentioned that it was a Reserve Chardonnay and used words like citrus juices, bright green apples and chalky minerality so definitely not the Tomich.
I would be interested to know what it is though....