It seems that iPhone fans always find a nit to pick with every new edition of the world’s most popular smartphone. Most years these gripes are minor, requiring no acknowledgement from Apple. Others are significant enough (like the iPhone 4’s antenna problems) to cause class action lawsuits and push Apple to give away free peripherals. This year’s big iPhone 6 problem is beginning to look like one of the latter.

The trouble began early this week when some iPhone 6 owners began reporting that their new smartphones were beginning to bend. iPhones have never been the most durable high-end smartphones – but they’ve also never bent from normal smartphone usage.

It appears that the issue is due to the larger size of the new iPhone models. Despite years of perfecting their carefully-machined case designs, materials science has only come so far. Aluminium is a relatively malleable metal and the larger size of the iPhone 6 Plus, combined with its thinner profile, is making that fact more apparent.

With the bending issue now known, Apple could respond to the scandal in a couple of different ways. The company could go the iPhone 4 route and give away free cases to consumers, which could presumably prevent bending. Or, Apple could simply tell customers that the iPhone habits they’ve developed over the years (such as keeping the device in tight pants pockets) won’t work for the iPhone 6.

Some Apple fans in the MacRumors forum thread where the bending issue was first raised are already defending the company, blaming iPhone 6 owners’ habits or bodies for the problem.

In the future, Apple will have to carefully consider whether aluminium is the right metal to use for larger iPhones – or whether metal should be used at all. Samsung, Apple’s closest competitor, has been using tough plastics for its Galaxy smartphones for years. Apple itself used a polycarbonate plastic in its less-expensive iPhone 5C models, and industry analysts have already predicted that plastics are the future of the smartphone industry.