I am fine with getting nothing, but I will get angry if you insult me after I just helped you. And telling me my skills are worth less than minimum wage (assuming it took more than 3 hours to find the bug _is insulting_).
Yahoo didn't agree to give you money, didn't hire you to test, and didn't even say "hey, can you take a look at this?". It's completely irrational to then say that a gift that they provided you is an insult. In fact, I'll go further: it reflects very poorly on your own character, and not theirs.