Roxybella, it is definately wrong, it is discrimination and you would have a case to take it to tribunal if you so desired. By discussing it with you, I expect your boss does not realise she is discriminating (unless she is so awful she says what she pleases and does not care), but ignorance is no excuse. You have said that you have no wish to take it further, but dependant on your circumstances, how you feel about your boss and your job, how easy it will be to find another etc, it may be a good idea to put something in writing to her, explaining that her comments concerned you and asking for a more formal explanation of what she said to you. This will provide you with written evidence. Even if she does not respond, you will have your letter/email to her to use as proof of the fact that she actually made these comments to you.
Hope this helps
Sue