Someone on another post said the seams might be shock absorbers since it looks like there's rubber between the seams. Apple had a patent awhile back that could detect if the device has been dropped. So if your device was having problem and you took it to apple they could tell if your product had been mishandled even if there was no physical damage.
"New Scientist points out an
Apple patent application published today by the U.S. Patent and Trademark Office that discloses techniques for digitally "
detecting whether consumer abuse has occurred in an electronic device." The application cites as examples assessing exposure to liquids, extreme temperatures, or excessive shock, as well as unauthorized tampering, all conditions which could cause damage to the device that may not be covered by manufacturers' warranties.
In general, such warranty and return policies are intended only to cover failures and defects relating to the manufacture or design of the product, and typically do not cover product failure that occurs as the result of consumer abuse. In fact, many warranty policies explicitly exclude returns or repair when damage from consumer abuse, whether intentional or unintentional, is the underlying cause of the product failure. For example, consumer abuse may include exposing an electronic device to liquids, extreme temperatures,
or excessive shock (e.g., the resulting impact from dropping the device). Consumer abuse may also result from tampering which may include any interaction with the device that is not related to operating the device in a normal manner (e.g., opening the casing or housing of a device and adding, removing, or altering the internal components).
Records of "abuse events" would be stored in the device's memory and be accessible through a diagnostic interface, allowing service technicians to more easily assess whether a given issue should be covered by the product warranty. The patent application also suggests that the device could turn off individual components or the entire device in response to an abuse event in order to reduce the potential for damage to the device.
In accordance with another disclosed embodiment, the abuse detection circuitry may be configured to disable operation of an electronic device upon detecting the occurrence of a consumer abuse event, for example, by disabling power to the device. Subsequent to disabling operation of the device, the abuse detection circuitry may be further configured to periodically check the sensors to determine whether the detected abuse event is still occurring and to re-enable operation of the device if it is determined that the abuse event is no longer occurring. By disabling operation of the device upon detection of a consumer abuse event, the risks of damage to the device from the abuse event may be reduced.
Many of Apple's current portable devices contain sensors that irreversibly change color upon contact with liquid, allowing service technicians to determine whether an issue may have been caused by consumer behavior that could result in the issue not being covered by warranty. The use of enhanced "abuse" tracking would enable Apple to monitor a wider range of potentially damaging events and more accurately assess the extent and timing of those events. "
https://forums.macrumors.com/posts/8232485/
link works now
I couldn't imagine an LED being in the seams, it looks like theres rubber in the seam, just like another post stated.
