I wasnt aware of this until reading the article just a few minutes ago and thought it was pretty interesting. The one I am going to post is from the South Florida Sun-Sentinel, just because thats the first one I read.

http://www.sun-sentinel.com/sports/s...a-sports-front

Quote Originally Posted by Juan C. Rodriguez, South Florida Sun-Sentinel
He (General Manager Larry Beinfest ) has gone from genuinely concerned for Reese's safety to "extremely disappointed" about the infielder's lack of communication.

...Reese left camp without notice Thursday and hasn't been heard from since. Friday, assistant general manager Michael Hill received a phone call from Mike Nicotera, Reese's agent, to let him know Reese had returned home and was safe.

Originally from South Carolina, it is unclear whether Reese was in Columbia, S.C., or in Charlotte, N.C., where he has family as well.
Latre in the article Joe Girardi is naming possible reasons, and suggests that he maybe doing "soul searching" and deciding if he still wants to play and whatnot. And then it goes on to talk about similar issues Girardi had during his career.

Appearantly though, since he has no permission, the Marlins could release him and owe him nothing (a little termination fee, but thats all). It'll be interesting to see how this one turns out.