Had you had high sugar intake before hand? I know someone who had this and they'd eaten a load of sweets before their appointment and it showed up
Happened to me once when I had a lucozade before my appointment x
Personally I'd probably wait until my app. If anything, they may book you in for a glucose intolerance test anyway to see if it's gestational diabetes but it's not like an urgent situation. I had glucose in urine twice at previous midwife apps (first at about 16 weeks) and they just booked me in to have the test at 28 weeks. Had it today - waiting for results
No harm in ringing them for advice regarding it.