I've always taken the approach that whatever, and whoever has told me something - that it's my responsibility to ensure that that information is true before i take it as gospel. I've ended up correcting consultants before.
It's always useful too to every so often check that any old favourites haven't changed. I use to eat pre-prepared polenta on a regular basis as it was free on green/ee. It changed sometime in the new year to being synned on all plans (1.5syns per 100g when i last looked - may have changed since then). I caught it early, but got talking to a guy on my street who was also a member back in March - he was still eating it as free.
Some will say that what's changed to cause it to be synned all of a sudden? It could just be a revision of the plan, or it could be that the ingredients have indeed changed. If it's a revision - it's up to you wether to change - "it used to be free, and i'll continue to keep it as free" if you like. Personally i prefer to change with the times - if that's what the plan says, i'm going to keep to the plan. (shame really - polenta, mushy peas, fried or grilled (in frylight) flat mushroom, and fried (fry light of course) egg - was a quick syn free meal).