The FDA requires that any side effect observed in more than 2% of the population during clinical trials or when released to the public be included in the attached (linked) document, the package insert. The "Adverse Events" start on page 20 but make NO mention of changes in behavior:
http://us.gsk.com/products/assets/us_flovent_hfa.pdf
However, everyone has a unique body chemistry that will react differently to medications. So, while he may experience the side effect, it may not be in the literature supporting the product.
Call your pediatrician and pharmacist, let them know you believe this is a causal relationship and ask what options you have.