You've got a possibility for a good thing. Your professionalism will
dictate how you are treated, and very likely what you get paid.
Given the very real benefits of exposure in this situation, I'd do it this
Sunday. Or you might try to call Sam before this Sunday, and say 'Your
staff seemed pleased with my performance, and requested that I come play
this Sunday. My normal rates are $x/hr. Is this within your budget?' If
he balks, I'll sometimes lower my rate a bit if it's a regular gig - if
they want me every week, or every two weeks, especially if it's a place
where other people can come hear me, I'll take a cut rate. But as a
musician friend remarked to me recently, people are usually willing to pay
you as little as you'll take.
If you can't reach Sam before the day, or he waffles 'Well, why don't you
come in and play and see how it goes' then it's harder - if it were me, I'd
do it. But after doing it once, I'd be very firm and say something about
this having been a gesture, and now I want to establish our terms.
This feels heavy-handed if you're not used to it, but I think it actually
reassures people somewhat when they think they're dealing with a
professional. So if you treat yourself as a professional, they will too -
and you deserve it.
Pamela Bruner
University of Kansas