Teenager dating a man?

im a 16 year old girl that met a 26 year guy.... he graduated from my high school and we met each other in a restraunt and started talking for hour . Then he asked me for my sn and i gave it to him. Weve been talking for about two months now and im starting to like him and i think he likes me seomtime but i cant tell. Someone told me that there is something mentally wrong with him to be talking to a "child" and to stop talking to him. But hes not nasty or perverted. We only talk on aim once a week because he works and i go to school and hes alwasy telling me to focus on my studies and he encourages me to not to give up on my studies. Also i know that he likes reserved girls and im reserved lol.He says that i have a future and warns me not ot go to the alley behind our high school because theres drugs . we jsut talk about school and things that we have in common. Should i stop talking to him ? and is there something really wrong with him to be talking to me ??