I was fishing at a local wildlife preserve in Jacksonville, Florida a few years ago and this little guy was curious enough to come in for a closer look. This was enough of a regular occurrence to us fishing that my kids named him Albert (go figure). He was around 4 to 5 feet long and in that picture he is only about 20 to 30 feet away from me. We made it a point to always respect his boundaries and he never came any closer than that.
The problem that arises is normally alligators of this size are afraid of humans and will leave if you get near them. I feel he was looking for food which means someone might have been feeding him. This will only cause issues for humans in the long run as this will become a nuisance gator when he is 6 to 10 foot long as he will attribute humans with food and then people get upset when he ventures into populated areas looking for food (small animals, cats, dogs, etc). Then he will probably be destroyed due to his ingrained behavior. Not his fault, he is just an animal looking for a easy meal, to which humans have provided.
If you ever see an alligator (or any wild animal for that manner; especially predatory animals), do not feed them. By doing so you are potentially causing the animal more harm than good. They have been doing fine and surviving long before humans and they do not need your help.