Not really! I don't know which test kit you're using, most of us use the API test kit. On the API test kit 0ppm ammonia equates to bright yellow on the colour chart. A fully mature cycled tank should read 0ppm at all times.
The only time you would get a positive ammonia reading is during the cycling stage. At this stage a positive ammonia reading is an absolute must. It means that your cycle is underway.
Also, you could also suddenly get an ammonia reading, referred to as a "spike", if you add fish to a tank, and the BB can't cope with the sudden added bio load of those fish.
This could well be what's happening in your case.
Keep your eye on the ammonia reading, and DO NOT feed until things settle down. You may have to do some partial water changes too. Hopefully your very new BB colony, if you had any in the first place that is, will adjust and things will settle down.
This is quite a critical time now for you, and your fish.