Continuity mistake: When Piper, Paige and Phoebe are having a food fight, Piper freezes the cake, then she throws it at Paige who suddenly has a mysterious stain on her top. Then Piper has orange food on her hands even though she hasn't touched anything orange, and the stain on Paige's top has gone.
Other mistake: During the second attack on Wyatt, when he lets his force field down the top of head is transparent from the special effects.
Visible crew/equipment: In the scene with Chris and David in the attic, a boom mic dips into the shot. (00:28:50)
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.