I also put new decals on the shooter lane and apron since the old one was scratched and smudged.  I sanded them back first then resprayed them and then put the decal on.  I did the shooter lane one first which turned out fine.  I then did the apron and had a problem - it bubbled after about the 3rd or 4th day????

How long did you let the paint dry for before putting the decal on?