Yep, definitely a bug. On img tags the attribute align="center" does not actually centre an inline image within an area, it would have to be put inside a block element.
ie. <h1 align="center"><img src="example.gif"></h1>
Anyway, all this is deprecated in html 4 onwards and using css would be a much better method for the future. Maybe the UBB version 8 rewrite will update this.
