Yes I have seen this! In my case it was in last summer, so it was the A/C.

Whenever I stepped on the brake, the blower would come on. I didn't mention it because people might think (or find out:)) I'm crazy. So one day with nobody else in the car on a quiet road, I hit the brakes 5 times in a row. Yup, the blower came on 5 times.

Then, just as mysteriously, the problem went away. Haven't seen it since. The only thing I did that might have fixed it was this: I took the fan control out of automatic and exercised it. (Normally I never touch this control. I had my 940SE for years and never touched it in any season.)

But what this has to do with the brakes is beyond me!