To clear up some information: I misjudged the distance before i used the ruler. It was 150 mm which was 15 mm too wide.
I had the bike upside down when I measured it, and at that time I thoroughly cleaned the bottom of the BB and checked where the chain stays joined the BB. There is no cracks or bends or any other obvious damage.
It did not take a lot of effort to compress the chain stays the bit over a half inch to get the axle to seat in the dropouts.
I thought long and hard about what kind of damage could have caused the chain stays to bend outward. Nothing came to mind.

Thanks for all the input other than the snarky replies.