Once the container has been in the fridge/freezer a couple of hours, go back into the fridge/freezer and "re-seal" the container (just give it a couple of extra pumps).  The container should still be sealed but when you take something from a warm kitchen to a cold fridge/freezer the seal can break or not be as strong.  By going back a few hours later and giving the container a couple of extra pumps; at that point, the container has been corrected to the fridges'/freezers' temperature and it will hold its seal better.