Expression calculates to very small number instead of zero

Here's a simple calculation:

<cfset ans = 50.4 - (336 - 285.6)>
<cfoutput>#ans#</cfoutput>

It's zero, right? Run this in CF9 and you get 2.13162820728E-014. I patched my code to ignore values less than 0.01, but this looks like a bug. Has anyone else experienced this issue?