Legal Question in Business Law in Iowa

They can write you up for any reason, good reason or no reason at all at any time because this is a right to work state.

That depends on several things. First are you under a union contract? If so look to the contract for the terms. Second, if the personnel department at your employer's business has an employment manual, look through it and see if there is a rule for reporting incidents. If not there is no law requiring any employer to "write up" any offense.