One thing that can cause this to happen, too, is not refrigerating long enough. If you stick one in the fridge, and open it in an hour, the CO2 doesn't seem to be dissolved in the beer as well as one that's been in the fridge a couple of days. Then, I get way more foam than usual.
My guess, though, is that the priming solution wasn't equally distributed when you bottled. It probably isn't contamination if everything else is ok.
Broken Leg Brewery
Giving beer a leg to stand on since 2006