Instant Search - Silverlight vs. HTML5

I have noticed something odd in the behavior of Instant Search between HTML5 (2.3.2) and Silverlight (2.3) viewers.  We have a large service indexed that we use to power Instant search for a site.  Our GIS data gets updated nightly, and we have been (and remain) concerned about how this may impact Instant Search. 

What's confusing me is that we have an HTML5 and Silverlight viewer configured for the same site - In Silverlight, the GIS data updates don't seem to create any problems with Instant Search.  But when using I.S. in the HTML5 viewer, the results are just wrong - type in an address and the result that is returned is a completely different address.  I can understand, generally, why this might happen given our nightly update process of the data, but I don't understand why it's not an issue for Silverlight.  The 2 viewers must deal with this differently, based on what I'm seeing.