Sometimes it's not until you've tried something new and react that you delve deeper into the other ingredients - even if the item is actually marked as gluten free.
Soya lecithin is often used in gluten free chocolate and other foods for texture and binding so that items don't separate. However, people who suffer from birch pollen hayfever and oral allergy syndrome may find they react to it by having a tingly itchy / swollen mouth, mouth ulcers, skin flushing and tight dry lips. You may also get abdominal pain, gas, nausea, vomiting and bloating (and assume it's evil gluten when it isn't). Often people also have allergic rhinitis type symptoms.
If you react to soya lecithin you may also react to other members of the legume family like:
fresh and dried peas, beans, carob, liquorice (often not GF) and peanuts.
Have any of you had adverse reactions - blamed it on gluten - only to look again and discover that it was soya lecithin that was causing you a problem?