intermittent brake light problem - HELP!

The brake light comes on intermittently and never figured out by dealership. Now it is past warranty, of course, and the dealership has pulled the codes once they cleared all but the one being generated by the light being on. They now claim it is due to a bad brake booster...a $1000 fix. Does anyone out there know enough about this subject to help me determine if this is really the problem? I haven't noticed any issues with braking with or without this light being illuminated. In fact, we have had this happening since shortly after buying this vehicle new.