Where did you see the puff of somke from? Was it from the charger itself (replace PDQ) or from the mains plug pins / wall socket? In the case of the latter, this is normal (ish). It is relatively common to get arcing between the mains pins and the socket on connect / disconect with switch mode power supplies like laptop power adaptors. On the mains pins of my adaptor, there are dark pitted areas on the tips of the pins where this occurs. If it's dark you can often see the blue flash of the arc and sometime hear the pop. In some circumstances this can also produce a bit of smoke. If it is possible for you to isolate the socket before removal /insertion, then you can stop this from happening.