They announced it last month. There was a thread on it here somewhere. The minimum now is $2.50. You didn't hear much about it because it was the national government who increased it not Macri. If Macri had done it then everyone would have acted like the world was ending.
And Macri is going to increase the subte to 4.50
En ese sentido, explicó que "para el trabajador o estudiante que realiza cuarenta y cuatro viajes mensuales se le descontarán de la tarjeta 4,50 pesos por cada uno de los primeros 20 viajes, 3,60 pesos para los siguientes diez, 3,15 pesos para los otros diez y 2,70 pesos para los restantes cuatro viajes, lo que da una tarifa promedio mensual de 3,83 pesos por viaje".
I will not throw myself into a political debate here, but I recall detailed reports about the 2014 increases on all TV-channels before New Year's. Clarin also wrote about it.
Thanks all! I agree that the fares are still extremely low (especially when compared to some of the American public transit fares that Im used to) -- was just surprised I hadn't heard anything about it!