YES it is.
I personally saw a 300 blow out the side panel after hours of tedious leveling, draining, leveling, draining, etc.
The thing was as perfectly level as can be done with "household" tools, and a week into the cycling process, it just failed.
Good thing it was in a basement.
The owner carved out the silicone and glass fragments, bought a new piece from a glass shop, installed and sealed it, and it's been fine ever since.