While infringement is bad, and it seems a pretty clear poaching of an idea, Johnny Cupcakes would have more credibility if he could properly identify a "jet" as he claims, from the obvious propellor planes in both shirts.
"I do not fear computers. I fear the lack of them" -Isaac Asimov
If it's any consolation, your design looks far better than the rip-off version. But the rip-off version looks so faded, and there has got to be way too much cholesterol and saturated triglyceride acids in those creamy extra large cupcakes.
Haven't heard of Urban Outfitters! Jonny Cupcakes is definitely a name that will stay with me tonight.....