By default, upgradation is deemed having been consentged to by the passengers. Only when you do not want to have upgraded, you need to express it and if wish to take further care, at the time of booking - should ask the counter representative whether he/she had marked (checked) the option that 'Upgradation is Not Required' ?
In your case, farely presume that this option is available to you. Still, only at a CRC (Computerised Reservation Centre), it can be enquired.