Opa Opa bourbon barrel aged milk stout

This brew looks like it is a Julio's (in westboro, MA) special. Grabbed a bottle because it sounded interesting. Looked at label 5.5% ABV. Not that I need a double digit aged stout all the time but what gives? I know milk stouts generally do not tip the ABV scale unless they are doubles or impys. But won't bourbon barrels get ABV closer to 8's or 9's? Anyone try this yet?