Subluxation is different to true dislocation, a messed up rotator cuff or particularly lax ligaments can mean your arm sorta 'slips' out of the socket but it self relocates pretty easily and doesn't always need intervention however if you have a problem with a lax shoulder some rotator cuff and general stability exercises are a good start.
Also an x ray following a dislocation that has been relocated will show a normal shoulder, there wouldn't be any evidence of the event unless you'd suffered a fracture at the time of injury.
(It may show a bankart lesion after the event but typically they don't show on x-ray immediately after injury)
Speaking as a qualified physio by the way, not meaning to come across as harsh but it does annoy me when people get the terms wrong and go asking advice off strangers on the Internet rather than go to a doctor first