yeah, so why is that?

according to wikipedia, that's a controversial statement. It says that forming of larger silanes (because of the ability of Si to form more than four bonds) contributes...that is, H's from other silanes are taken, building up a charge.

srsly. While I'm not an inorganic guy, and so my reasoning could be wrong, the basic info is in the first paragraph of the wikipedia article.

so how does that make it controversial?

there is conflicting combustion data, different labs got different results due apparently to different amounts of charge built up.

that doesn't show that it doesn't combust... just doesn't give the exact conditions. For methane i think it is far less likely to combust if it is in the gas phase

I'm no chemist, but perhaps it has to do with differing electronegativity?

thats the boring but true answer. larger atom and difference charge densities. for some reason the activation energy is lowered and under the right conditions (which are unspecified it seems) it will burn. its not that incredible, different groups share similar chemistry, but it is by no means identical.