Was the solution clear before you autoclaved it? Could be the glass flask used to mix it, or the glass bottle and cap, were not clean. I normally filter sterilize EDTA, the solution is always clear.
I am not sure of vapor. But did you let it stand in the autoclave for a long time (such as placing them in the autoclave and started autoclaving and come to get it after your class) this time?
For MS medium (a kind of plant tissue-culturing medium), some times some people will get slight yellowish color after autoclave. This problem has been discussed on RG, and some people suggested that this can be due to the medium stays too long in the autoclave, and components (such as carbohydrates) turn caramelized. But, I am not sure whether this also suit for the EDTA case.