Yeah, I used to use the act in turn buttons (especially when playing several table simultaneously) until I did pretty much the same thing in a cash game. The guy was short stacked and pushed all in with a decent hand. I was going to fold my two rags and wound up calling by mistake. And I didn't even get a fair chance to suck out on him, because to make things worse, another player had a real hand and reraised all in (which was a lot more than I could bring myself to call with garbage).
On the positive side, I've noticed that most software these days now lines up their check boxes with where their buttons will be, so it is a little more difficult to make this kind of mistake. So when I'm at a site like that, I will still occasionally use the act in turn boxes. But for the most part, I still click the button when it is my turn (which buys me the benefit of timing how fast I react to make it consistent or mix it up). Many sites still act on your act in turn selection immediately without randomizing the response time. This can give away a lot on someone's play.
