The "melting money" does seem to be coming in from various sources:
http://business.financialpost.com/20...n-summer-heat/
http://news.nationalpost.com/2012/07...spite-melting/
But likes other said, don't leave your money on your car dash. Or on a heater. Or on a toaster oven. At least I don't have to worry about my bills being ripped to shreds in the laundry anymore....
I do find that newer ones stick together. A couple days after the $50s came out, I accidently handed a cashier $150 when I was trying to hand her ONE $50. I am thankful that she was honest and pointed out that I had handed her THREE bills and not ONE. But once the bills get used some, they don't seem to stick nearly as much.