Mucus discharge in urine

My 13 yr old mix breed just completed 2 rounds of antibiotics to clear up a bladder infection. Her urine tested clear but she has been having occasional mucus discharges in her urine. I only see it maybe every 2 or 3 days. She has been incontinent all her life and it's been controlled with Proin. The Proin has become less and less effective even though I've increased the dosage to the max the Vet recommends. She can make it thru the night more times than not if I get up and let her out in the middle of the night. If I'm out for more than 4 hrs she will most likely need to be changed. Other than that she acts fine for her age. My Vet's office is closed for the next 3 days so I thought I'd ask if anyone may have some insight to this issue. With her age and lifetime of incontinence I'll probably be dealing with that long term. It's the mucus I'm concerned about.

It usually indicates infection. Has the mucus started after the antibiotics ended and the last urine test?

If so, it's definitely one for the vets. Do they have an out of hours 'phone line where they may be able to advise or even prescribe any meds that may be needed?