Typically, a car is serviced to to the full mark with cold oil, so yes you would be fine. Usually the add mark denotes a quart low condition(subject to engine size and manufacture). So if you add a quart when oil gets to the add mark, then you would be good to go! Oil expands when it is hot and contracts after cooling. You should always wait 15 to 20 minutes after shutting off a motor to allow for the oil to drain completely into the sump and this also lets it cool.... slightly. IMO Good luck and I hope it checks out ok when it cooled completely.