This may be a reasonable response for the short term (up to a week), but surely it can't continue indefinitely. However, although it's not the first attack involving liquid explosives, it is the first in the current political climate where fear is allowed to dominate and a "war on terror" has no end in sight. I wouldn't put it past the DHS and their counterparts to try and maintain this high alert as long as possible.
Does anyone recall what sort of precautions were taken after the liquid nitroglycerin explosion in 1994?