You sure they were F/A-18s (twin tail, twin engines, side intakes)? Reason I ask is that my office in Carmel was overflown several times by a 4-ship of F-16s (single tail, single engine, chin intake) early this afternoon. I figured it either had to do with the Memorial Day thing downtown, or practice for the race.
I used to see 4 ship F-16s once in awhile in Noblesville. I got to watch a couple of pretty good airshows from my porch that way! There's an ANG unit in Fort Wayne, perhaps they come south to play every so often?