A grant of restricted units from a previous employer vested and paid from a state where I am no longer a resident - I was at the time of the grant. Where do I owe taxes?

I left a GA company in 2014 and moved to Minnesota.  In 2015, I earned income from my previous GA employer for RSU's that vested in 2015.  GA state taxes were withheld on this income.  I was not a GA resident for any part of 2015 although at the time of the grant (2012) I was a full-time resident of GA.  Is this RSU income taxable in the state of GA (residence when the RSU's were granted in 2012) or in my new state of residence (residence when the RSU's vested)?  Thanks a bunch!