This is the first time I've noticed this issue even though I believe I'm using the exact same code.
I'm echoing $wp_query->found_posts with no query_posts filter anywhere in my loop yet my total results are showing inaccurately. The results themselves are fine but the total number of results displayed is pretty a little off.
The website is http://octagonfirstcall.com and the search I'm using to test is "david schwabb". It returns 34 total but the first (of 9) results has 15 matches followed by 8 in the second, and so on, totally over 34.