Oil can and will escape out of the dipstick hole. Don't wait to get it replaced. You will end up with oil everywhere but where it is supposed to be, and could end up with a seized engine. Go somewhere NOW and even if you have to pay someone $20 to put it in for you, it is far less costly than a new or rebuilt engine. Take a photo of the loose dipstick and the receipt and take that to the place that failed to put it back. Ask for your money and a free oil change. Oh - and watch where it goes in this time. Another thought, make them check the oil level and replace any oil that you have already lost. Yes, you will have already lost some oil. Look at the sticky mess on the inside of your hood, which will also be a clue as to where the dipstick belongs.
Shopping Southeast Pennsylvania, Delaware above the canal, and South Jersey since 2008