Hydraulic hell

[Brian Link]

Got a new issue this week that I need some input to solve.

My problem is a common one; the brake light stays on longer than normal
after start-up.
25+ assisted brake pumps with the car off.  I assume a good bomb.

Here is the part I need help with: I checked the hydraulic fluid
reservoir and it was pretty low, an inch below the min line.  I checked
for leaks and could not find a single one.  So I topped it off and went
on my way.  No more light for a day.  Then the light came back and
stayed on for a long time.  I checked the reservoir last night and the
level was way above the max line.  So I took some fluid out, started her
up and watched the level for 5 minutes.  Seemed okay, except this
morning the fluid was way low again.

Could this be the volcano syndrome?  Could this be a bad master
cylinder?

Thanks

Brian Link
Boulder