"Secret training" could mean anything, so I'm not going to take your word that you weren't sitting around watching them out the window or something. [He's onto that vague wording, mostly because he's had to deal with altogether too many people who favour vague wording over actually giving anything a straight answer.]

They can't go forever, so wanting to play is going to burn them out eventually. [They're spirits, and spirits can weaken and dissipate. Wasting energy on something like this seems counterproductive.] I found them when one of them tried throwing itself at the back of my head, so no.