My knowledge of this problem is a little limited so I can't tell you exactly what this may be due to. I do think it is worthwhile having an orthopedist evaluate your knee to see if anything else needs to be done to help this.
If there is a chronic dislocation problem it may begin to cause other problems such as pain due to the muscles constantly tensing up trying to hold the patella in place.
Advice and opinions given are based on the information provided and must not be considered an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.