Well, I'd bet a buck or 2 that it's TM and the custom they did originally for 98.7 KLUV in Dallas, called KLUV's Greatest Hits.
WMXJ has a long history of using TM jingles.
Funny thing is I believe Jeffrey T. Mason was on the air with these before leaving Dallas – last I heard he was in FL. and the jingles are following him!
Jeffro . . . . where are you now??