Re: Should I be upset??
Being a professional musician myself, I possibly can see the bassist's point of view. Does he do nothing but music for a living? If so, it might just be true that he can't do any other night.
When I plan my schedule, commitments are set in stone. When I take on a new project (band rehearsal, gig, recording session, lesson, etc...), I have to schedule it in in order of priority, and in relation to everything else. If I have a regular rehearsal or lesson time, I try to schedule other commitments around those times. If I get a gig that can only happen during one of those times, it takes precedence over the rehearsal or lesson. Maybe your bass player has other commitments that a gig would take precedence over, but not another rehearsal...???
One of my bands has a regular rehearsal time that gets shifted around on a semi-annual basis, it seems. Opportunities come up for the members to take on a new job offer (teaching position, different hours at their current job, etc...) and they negotiate with everyone else for a new time slot. The problem with this is that the rest of us have already shifted the rest of OUR schedules to make rehearsal work, often times leaving no room for budging either before or after. It's tough, but it's just one of those things that a band has to work with, especially bands that have full-time musicians.
Ask yourself: Does your band *really* need more than one rehearsal a week? I'm on a strict diet of "one rehearsal per week per band", unless a band has a unique situation like a last-minute gig and new songs to learn for it. But, for the most part, one rehearsal a week isn't even necessary (unless the group is just starting out or learning new repertoire), but we still do it, just to keep the momentum of the group going...