hello.

I just purchased a 07 tl and when i got it, i put my temp plate at the rear windshield without even realizing that i could damage the defroster grid.

when i took the temp plate off, i used baby oil and windex to get rid of the glue residue.

My question is:

does the grid break need to be visible in order for it to be broken? Or is it safe to assume that it is ok if i cannot see any clear breaks?

 

I think you'd be able to see it if it was broken.
You might be able to feel it get a little warmer than the surrounding glass if you turned it on, too; compare the one you're worried about with one that wasn't close to the temp plate.
I'll bet you are fine.
Welcome to the Forum!!