More specifics on bubbled area; advice sought

Here are some specifics on that bubbled area on the used unit we are seriously considering.

The Mrs. says the area in question is approximately 13 inches long, approximately 4 inches wide, and the bubble has a depth similar to a cupped palm of the hand, maybe 1/4" or 1/2".

Is this something anyone would be concerned about and can anything be done about it?

Thanks again