need some advise

Question
i was hoping maybe you could give me some advise, my husband and myself saw an ad online from someone looking to rehome their ferrets, so we ended up getting the 2 ferrets from them, the guy told us he had no info on the ferrets, he didn't know the sex, if they had been to a vet, ever,nothing. and i'm a bit worried about one of the ferrets.
his name is casper, he is very fat and fluffy appears to be healthy except he has gel like greenish to normal colored poop... i know that the "greens" is a symptom for ECE and i had read an answer from someone asking a question about that on here and what it said to do, but i was wondering... is there any chance that it could partly be a change in the foods he's eating cause i'm not sure what the previous owner was feeding him, but he hasn't lost any weight and he appears to be eatting just as much as my other ferrets (i have 5 total, and none seem to have the same prob.) also it sounds something like a farting when casper does poo, is it mostl likely ECE or could it just be maybe a sensitiveity in some new chages to his diet or just enviornment?
i've only had him for 4 days. should i take him to a vet right away? i plan to take him to a vet just for the fact i have no knowlegde of age, medical history... but is it a matter of urgency or just bring it up when i get him to a vet?

Answer
Alot of times when a ferret moves to a new home they get loose stools.  The greens are from ECE usually.  Almost all ferrets at one time or another are exposed to ECE and it will act up if they get stressed.  It will go dormant again just make sure he has plenty of fluids and continues to eat.  It would be wise to have him checked.  You can tell if a ferret is pretty old if his teeth (fang) teeth are clear on the tips.  That is usually a sign that they are up in age.  
I hope this has helped good luck with your new little ferrets.

Mary