Well, it's not like he's leering at her. ;-) He gives her a look of "earnest admiration" and "proved again, by the gentleman's looks, that he thought hers very lovely." (ch 12)

I interpret this to be like a friendly smile and nod, an appreciative gleam in the eye. That doesn't seem too forward or imposing. And more importantly, Anne, who is excessively attentive to propriety and decorum, didn't think so either. Though how much of that is due to her being flattered, may be another thing... ;-)