The iPhone 6 Plus is not only thin, but its body is made of aluminium, which bends quite easily compared to plastic and glass.
The controversy has been labelled 'Bend-Gate', and it's not limited to people deliberately mistreating their pricey new devices.
Some have reported their phones curving after merely being left in a jean pocket for a while.
"In one example, a new 6 Plus was bent during a day of 'dancing, dining, and driving to a wedding'," reports the Sydney Morning Herald.
Others have found their phones developing kinks after barely even bumping them.
"I've had significantly harder impacts to my 4s and never had any type of breakage or bending problems," one user told Apple fansite MacRumors.
The iPhone 6 Plus' screen is 5.5 inches across diagonally, and only 7mm thick. Most previous iPhones have been made of glass and/or plastic.
It's not the first phone with a tendency to bend however – MacRumors says owners of the Samsung Galaxy S4, Sony Xperia Z1 and the Blackberry Q10 have had similar problems.
"Any phone made of metal is still subject to the laws of physics," the site claimed.
Apple sold more than 10 million iPhone 6 and 6 Plus devices in its first weekend on sale.
