BTC transaction time now is even ~ 28 hours. Of course it is a long time, for example bank payments are faster. 
that case are rare , i can say it could happened 1 from 100,000 transaction. it's happened to me too sometimes. but i believe bitcoin are the fastest payment processor so far. bitcoin just need to make it consistent confirming the transaction in 1 conf only , i don't know how the techincal bitcoin network so i may could be wrong.