Yeah, I noticed on my older iPhone 4 and 4S that CleverPin wouldn't always work, given it would take a second or two to latch onto WiFi. My iPhone 5 is faster to grab the WiFi signal and so the problem is less so, but it still occasionally happens. I don't think its something the developer could solve, unless you installed a tweak like Insomnia to keep the WiFi radio on at all times... but then the trade-off is lowered battery life.