Of course there are no restrictions and you're welcome to contribute in any way! you can even contribute some mintcoins toward making an exclusive Mintcoin android wallet a reality.
I'd contribute regardless of license, once I've see further details/development.
Too bad you sold your mintcoins at 4 but I'm sure that if we can make this wallet a reality.. then the extra cost of buying back in will be well worth the expense and I look forward to your future contribution