Hmm ya, I could certainly see a positive feedback loop developing. Out of curiosity, do you regularly log into a google account and/or use services like gmail? I'm guessing not, since presumably that would give it plenty of data. (Unless you actually are a spammer... ;) ) Also, are you connecting from a location that Google might see as more likely to produce spam? (I would guess any non-"western" country to some extent, with Nigeria likely being at the far end of the scale.)
I have gmail open most of the time, but it rarely asks me to log in. It's only when I try to use other services that use recaptcha, or the rare occasions where I have to relog into google and mistype my password more than once. Last time that happened it locked me out of my account for 24 hours because I couldn't solve the captcha (although I could still access gmail on my phone).
