If kept in growing conditions, the flower should continue to grow and change colour for at least several days after first opening. So you may not know the "true" colour yet.
My "If" is based on experience of "just taking the plant into the house, so as to see and enjoy it" which usually stopped the flowers from growing so they never reached their full size or proper colour. Which I suspect is the case here . I shall look forward to seeing it when it has.