I'd say go for it with a quick way of ditching it if need be. Since both countries are in the EU and have no border checks I would think you should be alright. I am not sure why they would check just one bus over all the cars which would be the areas likely to have drugs smuggled. I'm familiar enough with the EU, but not enough to know what the expect beyond what I am told of the laws since I've never spent much time in a EU nation-state or crossed borders by car.