I'm using version 2.5.3 and PDF templates and this problem is not known to me. Did you maybe use a 'page break' at the end of your template?
Does this occur in version 2.5.4. as well? As the document generator has been changed significantly in this version, this version may work better for you.
If this problem occurs in version 2.5.4. then please submit a ticket in our support portal (support.mendix.com)
At this moment i work in 2.5.3. I can't go over to 2.5.4 (it cost to much time to test everything). Is there a solution / workaround for 2.5.3?