a non-problem?

During my recent Jeju/Andong walk, I had a lot of trouble charging my phone. In normal conditions, my phone takes 60-90 minutes to charge from 0% to 100%, if that. But during the trip, the charging times got lengthier, to the point where the phone would give me "slow charging" warnings that said it would take anywhere from 5 to 10 hours to charge the phone fully. So I contemplated taking my phone in for service once I got back. Now, however, I see that charging my phone at home or at the office takes only the usual 60-90 minutes again. So the problem might not have been the phone: it might have been either my portable charger or the charging cord. Perhaps the phone doesn't need to be looked at after all.