When either a supplemental or amended pleading is of such character and is presented at such time as to take the opposite party by surprise, the court may charge the continuance of the cause, if granted, to the party causing the surprise if the other party satisfactorily shows that he is not ready for trial because of the allowance of the filing of such supplemental or amended pleading, and the court may, in such event, in its discretion require the party filing such pleading to pay to the surprised party the amount of reasonable costs and expenses incurred by the other party as a result of the continuance, including attorney fees, or make such other order with respect thereto as may be just.