I have experienced this myself. However, minor bugs like this will probably be experienced until the full release comes out. Please don't freak out over this. It's actually quite common. In my area. ^^
All it is, from what I've gathered, is your phone's location detection (gps) isn't collecting the surrounding areas "data" quick enough to process it and submit it to your phone via the app. But as I said, it's just a bug that will be fixed in the full release.
Heres to hoping I was helpful instead of confusing ^^
Have a good day