I got a UTI after every catheter change, but it was usually within a few days of it. Your catheter has been out since July?
For a while after surgery our urethra is more susceptible to infection, partly because of possible bacteria still hanging around (bacteria is always present when we have a catheter), and the irritated tissue from the incisions themselves.
I’m not a doctor, but I would go ahead and take the antibiotics, then have a urine culture done afterward to see if there’s any remaining bacteria or yeast around.
I wouldn’t get too worked up about it though, as long as you’re still urinating fine there shouldn’t be a problem with the surgery itself.