{{ $hourInSec := 3600 }}

{{ if gt .Lastmod (add (time .Date).Unix $hourInSec) }}
  {{ with .Lastmod }}
    <span class="post-moddate">
      ({{ $.Site.Params.LastModDisplay }} {{ .Format ($.Site.Params.DateFormatSingle | default "2006-01-02") }})
    </span>
  {{ end }}
{{ end }}