Re: undercooked chicken?
Your chicken was fine. Chicken if cooked right should be tender and juicy on the inside. (as long as it was white all the way through). Pink in the middle is undercooked. You most likely cooked breasts, right? The outer part being tough and stringy. That because the outer part of the chicken cooked faster than the middle. you would probably know already if you had food poisoning. But just because you eat undercooked chicken doesn't mean you'll get sick.
As long as it wast tasty. Chicken can sometimes be hard to tell if it's done. next time your at the store buy yourself a cooks thermometer. You just stick it in and it will tell you what the temp is inside. Either meat, chicken, turkey, etc. It should also come with the what the temperature range for what your cooking.
Here's to good eating....