I would agree that if it's a fresh battery, you will be fine. I am not familiar with the maglite charger, but I highly doubt it's a float charger or smart charger. For anyone who does not know what a float charger is, it is a charger that applies charge until it reaches full charge and then cuts off until the self discharge has dropped the voltage down to a preset minimum.
The technology in these style chargers is not too complex however it drives cost up considerably. To give you an idea, Laptops don't even come with float chargers.
So while your car battery may be fine to take the minimal drain in between cranks, you are actually harming the maglite battery. you will get about half the possible lifetime. If it's more important to always have it charged and ready to go, then don't change your habits. However if you want the longest lifetime out of it, only charge it after almost completely depleting the charge. And only charge it for 3-4 hours MAX.