How much of a nuisance is it, really? On my phone it's a swipe down to reveal some commonly used settings, then a single tap on the WiFi icon. I suppose it takes no more than two seconds.
I don't know what you did and apparently neither do you, but you could have disabled Auto Reconnect for that SSID, meaning it would only connect when you manually ask it to, or maybe you selected the 'Forget this network' option for that SSID.