About a week ago I sent an email to the author of an iOS app requesting access to the source code after installing it and finding buried in a menu an email address and offer to provide me with such upon request.

I could not find anywhere where it states that it uses GPL code, but I suspect it does because it's an unofficial mobile version of a popular free and open source application/ file format licensed under the GPLv2.

Based on what I've read about GPL enforcement and reporting violations from the GNU website, I gather that I should give the author the benefit of the doubt, especially since they did at least put an offer to release source code upon request in the app.

I want to make sure I'm not being an asshole, but at the same time make sure my rights are not being ignored.

Is sending a second email and waiting another week sufficient before reporting it? Or should I give the author a month?

How have you exercised your rights under the GPL and handled potential GPL violations in the past?