Obviously, you transferred to secondary WAY too early if you're getting blowoff and clogging your airlock. Next time, wait until the ferment is finished to transfer if you're going to secondary.
As for this one... if you're putting out enough CO2 to blow your airlock off, your beer is most likely safe from oxidation. There's a SLIGHT chance something might have drifted in there on a dust mote to infect it or something, but I wouldn't sweat it.
"Science + beer = good!"