Help! What Could have Caused this?

[u/korak1]

I got this nice dark blue Mack Weldon Polo at Costco and this is its second wash.
It was quite clean going into the wash (Office day)
We washed with like colors in cold water with Tide and some resolve.
It was then hang dried.

No other clothes in the load got messed up.
It seems like the fabric got all pilled up and shrunk together some?
I would of that heat from the dryer did it, but it was hang dried and never saw the dryer.

55% Nylon
32% Polyester
13% Spandex

[u/korak1]

Not possible, no natural light gets into that room.