My 8yr old started Flovent several months ago. We saw some behavioral issues with her as well. They have largely faded but steroid medication in general seems to cause agitation, insomnia, irritability, etc with her. It's worse by far with oral Prednisone, but we see it with Pulmacort and Flovent as well. These kind of side effects have been documented in drug trials, more often with children than adults.
We always make sure she rinses her mouth well after the Pulmacort or Flovent to reduce chances of getting thrush.