Digital content licensing startup GumGum has raised $2.6 million in funding, according to an SEC filing just filed. GRP Venture Partners led the round, with participation from previous backer First Round Capital. The L.A.-based startup has raised around $3.8 million in total, including the first tranche of a $1 million first round from First Round and Crosscut Ventures last year. The company declined to comment on where the funding came from and its plans moving forward.