yes it would be, but i'm assuming that you are talking about a 10ml vial right? if that's the case, you should get a filter and a sterile vial. If the rubber stopper popped out and the seal broke, as long as you didn't touch anything inside the vile, inside the stopper, and somehow managed to place it back together, sure you can keep on using it. BUT, if you think you can just inject out of the top you're running a risk. it's a steril environment inside there and now you have exposed it to potential contamination..
after you filter it, inject your oil into another vial with an extra needle (without the syringe) sticking out of the top. slowly inject the oil into the new vial . once you have finished, pull out the extra needle (for breathing while you inject) and then bake at 250 degrees for 15 minutes. you'll be good to go.