Yes, it's possible.
Before the urine test at the urgent care, how long prior had you urinated? Had it been at least an hour? When you gave the urine sample, was it a first catch, meaning when you first started peeing, the first part of your urine stream went into the cup?
If it had been less than an hour or it wasn't your first catch, the test may not be accurate.
Also, if you'd taken any antibiotics within the 2 weeks prior, it could give you a false negative on any of those tests.