wrap-option question

I am generating a PDF using XEP and 1.69 of the stylesheet and have 
added the following to my customization layer:

  <xsl:attribute-set name="monospace.verbatim.properties"
        use-attribute-sets="verbatim.properties monospace.properties">
        <xsl:attribute name="wrap-option">wrap</xsl:attribute>
        <xsl:attribute name="hyphenation-character">\</xsl:attribute>
    </xsl:attribute-set>

However, in some cases, rather than wrapping the text, it tends to 
"shrink" the text or tighten it up rather than wrapping...any ideas 
what's causing this?

Thanks
Kari

-- 
Kari Bourgeois
Technical Writer
Pyxis Technology
512-637-0519