I wonder if someone had it as a pet and released it?
Perhaps.
They do migrate. They are all over NE TX. Very shy usually. Have seen them here at Cedar Creek and our other place in LA.
I saw a movie from the late 70's or early 80's about a baby gator which was flushed down the toilet in NYC, and thrived in the NYC sewer system, and then went on to terrorize NYC.
We have them west tn
Similar latitude I think
I remember a few years back there was a gator spotted in a marsh/creek behind the football field at S.Oak Cliff(?).
They moved practice to another campus until TPW removed the animal.
There is a gator preserve near Parson’s Slough in SE Dallas County. Just South of 175 and 635.
I have also seen them in the Sabine near Lindale.