According to some reports on Reddit, players have complained that after playing on Nintendo Switch for an extended period of time in dock mode, they have noticed a wrap forming at the back of the console as if the plastic is slightly bending.
This report has been confirmed by several more users, Nintendo Switch community has formed a theory that it may be happening due to the fact that the switch screen is off in docked mode. The back plastic is against the metal back causing it to heat up.
However, players that evenly distribute their time between Switch handheld mode and dock mode have not complained about such an issue.
Since only a few players have reported this issue; we can speculate that it would just be a manufacturing fault as previously seen in the Joy Con and its synchronization issue.
The ones that are complaining about the issue have also stated that even as Switch is bending it has not shown any performance issues.
It has almost been a month since Nintendo launched Switch so such hardware issues can be expected. Nintendo faced some similar issues with the Wii users because of its weak wrist wraps, that ended up breaking many Televisions while playing games on it.
But overall, Nintendo is famous for producing good quality products, so these issues are unlikely to occur on every Nintendo Switch console. These few cases of bending plastic are rare and can happen due to varying reasons like playing on docked mode for far too long, or insufficient cooling in the room e.t.c. so no need to worry about it too much if play on dock mode for a moderate amount of time.
If you are facing this warping issue with Nintendo Switch then you should probably contact Nintendo customer service for support.