Your legislation in Iowa clearly states that a) there has to be disclosure of the full term on the brokerage authority, and b) any details of a protection agreement have to be produced by the broker
If you've got a copy of the listing authority it should settle it all for you....
a)
193E—11.1(543B) Listing brokerage agreements. All listing agreements shall be in writing, properly identifying the property and containing all of the terms and conditions under which the property is to be sold, including the price, the commission to be paid, the signatures of all parties concerned and a
definite expiration date. The agreement shall contain no provision requiring a party signing the listing to notify the broker of the listing party’s intention to cancel the listing after such definite expiration date. An exclusive agency or exclusive right to sell listing shall clearly indicate that it is such an agreement. A legible copy of every written listing agreement or other written authorization shall be given to the owner of the property by a licensee as soon as reasonably practical after the signature of the owner is obtained.
b)
193E—11.2(543B) Enforcing a protective clause. To enforce a protective clause beyond the expiration of an exclusive listing contract, there must be a provision for the protective clause in the listing contract which establishes a definite protection period, and the broker must furnish to the owner prior to the expiration of the listing the names and addresses of persons to whom the property was presented during the active term of the listing and for whom protection is sought.
You can get further info
here
Cheers