Be Careful What You Witch For - S2-E22
Other mistake: Phoebe says to the genie "you've been stuck in the bottle for 200 years?" Later the genie says he will be an unwelcome house guest and not put the CD's back in their case. If he was in the bottle for 200 years how would he know of CD's?
Other mistake: After Sam uses the powder on the sisters, erasing their memories, they're visited by Leo who starts to say "he must have gotten the powder" and one of the sisters finishes with "our mother." But in a later episode we learn all white lighters have this powder.
Other mistake: When Prue astrals back to recite the spell to reverse the awakening spell, she and Phoebe don't actually complete the spell, they just recite the first paragraph "What was awakened for its sleep, must once again slumber deep" the rest according to the book of shadows is "return the disease to whence it came, so life can ease back to the same".
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.