Not a big issue at all, compare to my situation where I have to spend 2 gallons of Antifreeze coolant during 1 month period of time. I know that I have a crack on top right of my radiator that caused specially when high acceleration occured,it push water into the top that make it's way down around top corner. Now, I'm just waiting for the summer to arrive so I can replace my entire radiator, as it will feel more comfortable to work ouside.
In your case, seems like you have one of the leak down air from one of the hoses where water flows. Get under the car specially when engine running hot, look around and you should spot some wet area that lead to the issue.
2001 X5 M62 4.4i