To be fair, that depends on whether you're following section 3a or 3b (let's ignore 3c for the moment) of the GPL (and let's, for the sake of argument, assume version 2 of the GPL to save me from actually having to look at the MySQL website to find out which version they use). If you choose 3a, then you must accompany the binary with the source code at the time of distribution. If you choose 3b, then you must "accompany it [the binary] with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code" (emphasis mine).

Of course, this is just my interpretation, IANAL, YMMV, ABCDEF, XKCD, WTF.