This is very common in dance - and I've experienced this a few times. It can be a great exercise in how fast you can pick up what's important for cuing and communication with the choreographers/designers.
Also, in those situations, you may want to find out what is truly expected of the SM. The run may be very short, you are not expected to give notes, not make sign in sheets, etc - just call the show. I've had this happen several times with a particular dance company - they had a company manager and a costumer that basically handled everything, except calling the show. It did make me feel very disjointed and not a part of the company, but I was brought in at the last minute, so there was no time to fit in.
These aren't always the most satisfying gigs, but they do have fill employment gaps.