Prosecutors say Richard Soto of Corpus Christi had served time in the Coastal Bend Detention Center but was out when he noticed the girl with her father.
A federal judge Tuesday sentenced Soto, whose new sentence begins after the inmate completes his current term.
Soto in 2002 was convicted of being a felon in possession of a firearm and sentenced to prison, followed by three years of supervised release. He was rearrested last July and sentenced to another year for violating his release.
Prosecutors say Soto last November threatened to sexually assault the guard and his daughter the next time he was freed.