Incremental does not work on first change event

Most of our input controls have an associated alert image 'invalid.gif'
Each input control with incremental="true" does not seem to function on the first changed event after the page has been rendered the first time.
Any revisit to the input control functions properly.

For example:
xml:

<MinimumPasswordLength>10</MinimumPasswordLength>

xsd:

<xs:element name="MinimumPasswordLength" type="i1to40Integer"/>

<xs:simpleType name="i1to40Integer">
	<xs:restriction base="xs:integer">
		<xs:minInclusive value="1"/>
		<xs:maxInclusive value="40"/>
	</xs:restriction>
</xs:simpleType>

XForm:

<xforms:input ref="MinimumPasswordLength" incremental="true">
	<xforms:label class="Password">Minimum Password Length</xforms:label>
	<xforms:action ev:event="xforms-value-changed">
		<xforms:setvalue ref="//PasswordOptions/@changed">true</xforms:setvalue>
	</xforms:action>
	<xforms:alert>
		<img src="./images/XForms/invalid.gif" alt="" />
	</xforms:alert>
</xforms:input>

The input control initially displays '10'
if I type in an extra '0' to produce '100' there is no alert image displayed.
if I type in an another '0' to produce '1000' an alert image is displayed.
if I delete a '0' to produce '100' the alert image is still present.
if I delete another '0' to produce '10' the alert image disappears.
If I type an extra '0' again to produce '100' an alert image appears.