Why does Yahoo Answers change my words?

So, I answered a question in the hunting forums about a gas p.i.s.t.o.n. system.

I talked about AR-15s, Eugene Stoner, and a bunch of gun companies. But every time I talked about the piece of machinery that pushed the bolt back, I used the word ending with N and starting with pisto

So, when YahooAnswers displays your answers, they always take a few words and make them blue with a bunch of dots underneath them, which denotes that they are actually links use that term in a searchengine that brings up sales related to those words.

Yahooanswers changed my word ending in N (piston) to pistol ending in L when their software 'mined' my answer looking for good keywords to link off of. It then converted the four or five other times I wrote piston ending in an N to pistol ending in an L.

What the heck is up with that? I could see their programming accidentally changing the first one but not the next. And yes, I know it isn't a typo by me, because while I make a ton of typos, I'd not be that consistent. I'd at least have one pistone as half the time when I try and write pistol I end up with pistle; or pistole