Think of the "TA" as "Thermo Acidifier". I don't know if that is the company's logic, but it is certainly mine and helps me keep from confusing thermo cultures. I think the same way with Meso - "MA" = "Meso Acidifier".
So the "TA's" mission is to gobble lactose and acidify quickly, but it does not do a very good job of utilizing all the lactose. That's where the LH steps in. The LH100 does not metabolize lactose as quickly, however it finishes up where the TA stops. Once the TA hits a certain point in the time curve, the pH drops like a rock. This is one of the reasons that thermo cheeses often stick to cheesecloth and everything else. So that's exactly what you are seeing with the Mother Cultures. The TA acidifies quicker, so it doesn't need to incubate as long. Like I said previously - usually 6 to 7 hours. Another way to manage things is to use less dry culture to prime the milk. Cut the bacteria in half and it will take longer. Bacteria grow logarithmically so it will NOT take twice as long.
From a practical standpoint, your TA has over acidified and will not be as robust as it should be. Many bacteria are still alive and viable, but some will not survive the acidic conditions. You can either use a little more or give it more time to ripen. In any case, use it soon, and don't expect it to last too long, even if frozen. Keep in mind that when using a Mother Culture you are not only adding the bacteria, but you are adding the acid that was produced as well. So you don't want to add too much MC either or your acidity will be lower than it should be at rennet time. Milk for MC is cheap, so personally I would make some fresh.