The story began when many owners of the Galaxy S4 started bringing theirs to the carrier, complaining from overheating, endurance degradation, and even straight-out swelling of the unit. Half a year since introduction, the issue seemingly reached endemic proportions, with carrier insiders reporting up to 30% of their Galaxy S4 customers coming with such complaints, so not isolated incidents...Source: http://www.phonearena.com/news/Samsung-acknowledges-Galaxy-S4-swelling-battery-issue-offers-free-replacements_id48352
