I have noticed when searching for friends that sometimes it seems random people pop up when I search for one person, and then search for another, I assume this is down to caching and trying to find the best match possible in the cache whilst typing. These results quickly clear away, but it makes the search feature feel strange. This is most easily replicated by doing what I do to check for new users in the app.

Go to the add friends tab and type and search one letter only. eg:

A -> Search -> Delete 'A' -> B -> Search -> Delete 'B' -> ...