Marijuana does not cause Gynecomastia per se.
Statistically though, people who use Marijuana are more likely to have Gynecomastia than non-users.
The question is: How lucky do you feel? You already know that you are a man who is prone to breast growth so it might be presumed that your risk is above average.
Don't let yourself be fooled by the fact that use for a few months has had no apparent effect. If MJ would cause regrowth, it would occur over time. by the time you noticed it, it would be too late.
As usual, prevention is preferable to cure.