Is the Haber Process here proceeding at positive Gibbs free energy change?
It's all about the pressure! The Haber process requires a pressure of about 200 atm. This is how the process becomes favorable, since LeChatelie's principle says that increasing pressure shifts toward the side with less moles of gas.

As long as Q is smaller than K, the reaction will go forward. For example, if nitrogen and hydrogen are supplied at stoichiometric ratio and 1% of a given reaction mixture is product, we would have the following partial pressures:

$$ P_\ce{N2} = 0.2475 \times \pu{200 atm}$$

$$ P_\ce{H2} = 0.7425 \times \pu{200 atm}$$

$$ P_\ce{NH3} = 0.01 \times \pu{200 atm}$$

Accordingly, Q would be 

$$ Q = \frac{2^2}{50 \times 75^3} = \pu{1.9e-7} $$

In the Haber process, the concentration of product is kept small by continuously removing product (liquifying ammonia at low temperature) and feeding the remaining reactants back into the reaction mixture.