Here's what happened:
I basically caved in and asked a fellow SM at this theatre how one would reorganize the cue list in the lightboard. It ended up not being all that difficult. SO, I ended up doing a lot of extra lighting work for this theatre and not getting paid for it. However, I should have made it clear to them that I would not be executing an entire hang/focus/lighting design for the festival version of the show without getting paid a designer's fee. Once I did that, I set a bad precedent.
This particular theatre has no production staff and has a history of preying on the generosity of others - I've seen Directors organize all their own marketing and fundraising, costumers pay for their costumes out of pocket and never get reimbursed, actors never paid for their final week of performances, composers given fraudulent ticket sales breakdowns and cheated in royalties, health inspectors lied to, audience members bleeding in the lobby with no house staff on duty, loads of bounced checks or checks with double or triple tax withholding for no apparent reason, dangerous working conditions, and the list just goes on.
Needless to say, I think I'll be more careful about sticking to my employment agreements from now on, and refusing to do favors. And I would not ever work for this company again, nor would I recommend it to anyone.