Good thinking guys!
There are a couple of possibilities. 1) damage to the sphincter muscle and 2) inflammation/damage to the nerve. Both have good news generally. There are several methods for surgical removal of the gland - some include cutting into the sphincter muscle and then reapposing it. Also the glands are just ventral to the control nerve. The nerve is small and often not possible to localize. The nerve can easily be transected - especially if the gland lives a little high and the nerve lives a little low! Also just the surgery itself can lead to normal post operative inflammation which can involve the nerve.
The good news? Well, your description sounds like she is having a little difficulty in control - as opposed to complete fecal incontinence. The 'partial' control means that the nerves are to some degree intact. In all of the scenarios described above - control usually returns to normal. This surgery always runs the risk of fecal incontinence either partial or permanent. Luckily the surgery is rare to have permanent fecal incontinence.
I agree with your plan though to contact your vet on Monday. It sounds like with some time, things should turn out well. Is there any unusual swelling or discharge from the incision site?
Good luck and take care.