The FBI are investigating the reship companies not the random people using them, or they would have let you get the phone and charge you after. Noones spending time and effort to prosecute some random dude in another country for a couple pixels its not worth their time or money.
If what you did was illegal and they wanted to charge you, they would need to extridate you to US and try you there. Does that sounds like a real possiblity to you?