Would you charge extra to insert Flash detection?

I have a client who’s very happy with the Genie application I made for him
(demo here):
http://www.evynco.com/genie2.html

I forgot to include a Flash detection script.

Some of his clients don’t have Flash so he’s come back to me.

I’ve now written a Flash version detect page with two simple choices, go to the company’s home page or download the latest Flash Player.

There are six versions of this Genie, so I made six versions of the detect page (only difference was a hyperlink).

Took about half a day, but do you consider that I should have included Flash detection first time ?

Or would you charge this and risk upsetting the client ?

Hmm…