It is difficult to answer your question without the specifics of the situation. In general, if you received a halachic ruling about a particular situation, you may follow that ruling if the same situation comes up again. However, sometimes there are relevant details which may affect the ruling, so it is best to ask again if you are unsure.
For the future, when you call your rav with a question you can ask him if you need to call back every time you encounter that specific situation or if you can simply apply his ruling to similar situations that may arise.