I just updated to the latest version of relevanssi, and I'm getting this error on some of my searches.
it seems to occur any time "0" is part of the search as in "0 awg terminals" or "0 Gauge Terminals" but "10 AWG Terminals"
I still get results returned, although only the word "terminals" is matched.
http://wordpress.org/extend/plugins/relevanssi/
Thanks. Looks like I can reproduce this error on my site. Shouldn't be too tricky to fix. Next version will fix this.
Those numbers aren't matched in any case, as the minimum word length for the search engine is by default 3 characters.
This will be fixed in 3.0.4.