Hi Mike:
Maybe, maybe not -- tough to say without actually visiting the site and observing the trees and the symptoms. This could be stress induced by last year's drought, or it could be something else.
I would encourage you to contact your local IDNR district forester to schedule a site visit:
Illinois Technical Forestry Assistance:
http://web.extension.illinois.edu/forestry/pdf/tfb-nres-201-13.pdf