When playing the card game Rummy, when you pick up from the discard pile must you use that card in a set of 3?

I was playing the other night, and I noticed that someone had down the 4, 5 and 6 of clubs. The 8 of clubs was in the pile and my opponent had the 7 of clubs. So he picked up the 8 and put down the 8 and 7 clubs only. Propecia pill whithout prescription Is this allowed