The person asking for clarity may be trying to preserve goodwill.

Questions can look like doubt and function as care. Someone checking what exactly was agreed is often trying to avoid the situation where they get it wrong, you are annoyed, and something perfectly good is damaged over an assumption. The small awkwardness of asking now gets chosen instead of the larger one later. Precision is frequently consideration rather than suspicion.

When someone asks you to be more specific, answer the question rather than reading it as mistrust. If you are the one unsure, say that you want to get it right, since that is usually the true reason.