Brakes

[D-Rider]

You sure it was air and not steam? If you have water in the fluid it would boil in the caliper and expand when that hot.

Very good point - and why they tell you to use new fluid from a sealed container rather than from your old half-full bottle.
I try to avoid fluid changes on damp/humid days too.

[Dalemac]

I hadnt thought of that, but it looked like an ordinary air line. i guess it could have been, but always use a fresh bottle of fluid, as per d-rider mentioned above.