I'd think it could be possible, but Islamic terrorists haven't been singular in terroristic pursuits up to this point. They tend to be organized in such a way that they'd be more of a mind to spread groups out all over the country to hit multiple regions. They would also be of a mind to want us to KNOW it was Islamic terrorism.
This guy (or guys) is just a nut.
That's what I think, too, what good is a terrorist act with nobody claiming responsibility?