Check on length string results in translation of tags

Hi,

When I use:

                Field::inst( 'am_templateblocks.content' )
                    ->validator( Validate::maxLen( 4000, ValidateOptions::inst()
                    ->message( 'Dit veld mag maximaal 4000 karakters zijn' ) ) ),

The input of "<section>" results in the unexpected "<section>"

Why is this? Is this a bug, or can it be configered to accept tags?