Correct answer: Nope. It is whichever comes first. Time or mileage. Time is from the in-service date which as listed was 1/4/12. So 1/4/17 is when it expired regardless of the 100k mileage coverage.
Grey area answer: What is at dealer discretion is something we called "Goodwill warranty". Meaning had you come in in February with this issue, sometimes the dealer would go "Ok, we'll handle this, and then submit to GM and see if they will cover." However, If they don't cover it, it's more or less on the dealership. Which leads me to my next point as to why they probably won't do this... It's a transmission. Transmissions aren't cheap, and labor to R&R them isn't cheap. Couple that with being 10 months out of warranty, I highly doubt they would go this route. For something simple and relatively cheap, yes. But a transmission, probably not.
A potential, hail mary grey area is to play games with GM's system. I won't say that we did this, but sometimes "errors", say along the lines of VIN#, occurred and we could play things off in the system. Think of it as robbing Peter to pay Paul kinda nonsense. I don't know what GM's controls are anymore, but again, "errors" occasionally occurred. But here, much like above, it was on cheaper things to R&R.