Why does Morris grow pale after he makes his third wish on the monkey's paw?

Morris grew pale remembering his third wish on the paw..... he'd already had the wish, and from his paleness, we can infer it didn't turn out so well.

"Well, why don't you have three, sir?" said Herbert White cleverly.
The soldier regarded him the way that middle age is wont to regard presumptuous youth."I have," he said quietly, and his blotchy face whitened.
"And did you really have the three wishes granted?" asked Mrs. White.
"I did," said the sergeant-major, and his glass tapped against his strong teeth.
"And has anybody else wished?" persisted the old lady.
"The first man had his three wishes. Yes," was the reply, "I don't know what the first two were, but the third was for death. That's how I got the paw."