When Danielle came in for the explosives Locke made the comment ' Be careful it's unstable'.
This seems like an obvious statement since Danielle is the one who showed the losties where the dynamite was in the first place.She should by now know it is unstable.

I think this comment was actually just so they could get the unstable line out.Characters like Locke,Danielle,Ben and even Jack are unstable.
Those particular characters are similar to the dynamite,they could easily explode at anytime.

Stacy Lane