Yup, I believe fishfreek
is right on the money.
I ran into a similar situation with certain brands of Silicone sealant. After doing tons of research, I found that some brands label the stuff "not for use in aquariums" so they do not have to worry about any law suits caused by livestock loss. The same product labelled "aquarium safe" can sell for more money. However, I am not saying that it is a ripoff or anything, they probably take extra precautions not to contaminate the "aquarium safe" product or sterilize it in the process.
, just be thourough when washing it.