Definately talk to Jamie! I just recently got a gecko that looks absolutely healthy but the people I got her from said she was in a tank with a very sick gecko that got extrememly skinny and then they gassed it cuz they didn't know what else to do. This was a friend of my parnents friends gecko. I wasn't really interested cuz it was a normal but I didn't want to leave it there cuz if they couldn't get rid of it it too probably would have been gassed. So I guess you could call it a rescue. I'm still waiting for a fresh sample for a fecal. I just picked her up on Saturday night and it was impossible to bring a fecal in on Sunday or tonight, so probably tomorrow or Wednesday when ever I find a fresh one I'll be bringing it in. Because she was housed with the other she most likely has whatever that one had.
Jamie told me that it probably wasn't worms but to get a crypto test done as well. This is very important. A bit expensive but for a free gecko, you can't really complain much.
Good luck with him/her and keep us posted.