[Closed] Bontrager Rhythm rim, inner face cracked

I broke a spoke on the rear, Bontrager Rhythm wheel on my 2009 Trek EX8.
I pulled the plastic rim protection strip away from the inner face of the wheel, so that I could remove the spoke nipple and short, adjoining length of spoke.
Imagine my surprise when I noticed a circumferential crack that runs around the entire inner face of the rim of about 0.5 to 1mm width. Without removing the rim tape all looked well.
No idea how long it's been like that (or what would happen if I kept riding it), but it's taking the short trip to the recycling point tomorrow.
Isolated incident?