It is not uncommon to have lenders communicate Orally (via email too) regarding terms so when the final agreements are placed in writing there is only one g0 round for signatures.
Looking at your market stats it appears that you have a downward trending market in terms of values, is that correct? Balanced from the inventory standpoint, or is it seller's market?
Your buyer needs to know the type of market. If months of inventory is below three months (which might be the case here with 450 homes for sale and 260 homes recently sold) then your buyers need to be aware that the sellers can "make the rules".