I know that my car was only built the last week of August so am hoping that things may have been sorted.

 

The white stuff shown in Bryants pic is probably road dust picked up after using the wiper or after a rain.
If you stuff leaks, call your service advisor and schedule the car to be fixed. I did this and no worries since. You could possibly wait for it as the job doesn't take that long to accomplish.

I believe the problem is known and the fix is in as both my minis did the leak and both have been fixed...no questions asked or BS given.

 

I've now had my car for a couple of (hot) days and I'm pleased to say it doesn't appear to have this issue.

 

Have you used the wiper fluid yet? I didn't have the issue until after the wiper jets were used the first time, about a month after buying the car. Sorry if you've answered this previously. Just curious...I had them drain the fluid and Im currently running without because the fix didn't work for me.

 

admittedly I've only used them twice. I should say that before the car arrived at the dealer I made a point of emailing them a request to ensure that the car didn't have this issue to save any journeys for warranty work. they assured me by email that it was a known problem which had been a factory fix since April and that as my car was an August build it should be fine.