If the fluid was low, you may have knocked the little proportioning
valve or whatever it's called in the brake line junction tee.
I usually get rid of those tees and go back to the simple 67 brake
system because of that "safty" feature that is a real PITA.
The click would be the valve setting off the brake failure lamp, the
lamp that goes on after you say Oh Sheet no brakes, well there is a
light to let you know this because your foot on the floor is not enough
;) But once that valve moves, it has to be reset.
I never did this, I get rid of the valve. When the valve is off kilter,
the rear brakes will not engage.
That's my opinion, and it has happened to me with most 68 and newer
Spridgets that's why I bought a bunch of NOS 67 only brake master :)
Toms River, NJ