Meringue - why they aren't always the safe option for a gluten free desert

We stopped off in Stroud for lunch after a visit to Shipton Mill to discuss the possibility of bagging my flour.

After a disappointing lunch ( it turned out the chef had put soy sauce in everything but the hummus in the cafe) we had a coffee at a delicatessen.  TT had some delicious meringues with vanilla cream.  As he said they were very good I had a spoonful - and then I spotted that the tongs the waiter had used were brown at the ends - they were obviously used for the chocolate brownies too.  I am normally super careful about checking how the staff avoid cross-contamination but forgot to this time.