I recently had a disc brake conversion done, and on the way home from a cruise night my buddy, who was following me home, said that my brake lights were "surging" or coming on when I am just driving. They do work when I am braking. Both running lights work and signals are working.
Is there some sort of adjustment that can stop this? Or is there a possible short.
I had a shop do the conversion.

check your brake switch I did the conversion and my switch was out of adjustment and it flickered when going over rough roads.

I think dawg (harry) is right sometimes your pedal height changes just a bit because your booster has an internal return spring and your manual had a manual spring so your brake switch might need re-adjusting.

I think the fellow who did the work reinstalled the original return spring to bring the pedal back to height. Should we only be using the internal return spring? Could that be the problem with the lights? He said that pedal seem low without the original spring!
Thanks for any help. The car's brake feel is perfect.

Factory power brakes didn't use a return spring for the pedal. I'd adjust the switch. It's very easy to do.

Did you convert to power disk? If yes, then there is no return spring. Only manual brakes had the external return spring. Also if you converted to power, there should be a brake light power sw bracket installed which drops your pedal about 1" below your clutch. Ricks sell it p/n PT-83. If your car was already power, then it should already be there, and then it sounds like it is just a push rod adj. to get your switch set right.