Are you on medication for your diabetes? If so, which ones?
Do you have a glucose meter and can you test blood glucose?
If not on specific medication, you should only pee out glucose if your number is above approximately 11 mmol/l, so it's likely you went higher than that, unless you are on an SGLT2 inhibitor (medication ending in flozin).
If you're normally on a keto type of diet, this could be the cause of seeing ketones. Do you usually see ketones when doing a dipstick test or is this unusual for you?
One of the problems with dipsticks is that they look in the past. So I guess it could be possible that you see the dietary ketones from before the shortbread, and the glucose from after the shortbread.
Testing later tonight again makes sense to me, unless you feel unwell or are worried. In that case, please call for medical advice.
DKA isn't something to joke with, so please don't ignore any symptoms if you have them.