If you're in Romania you should be fine. If they find out you've unlocked it, they'll probably tell you your warranty doesn't cover it, so you'll have to be that annoying Mr. Know It All guy for a bit and tell them why they're wrong (Google it, and there's been a thread about it on this forum as well with some links), they'll be intimidated and will believe you on your word, then they'll fix it and you'll be happy and buy an ice cream with the money you saved.
If you're still planning on relocking just to be safe, I don't think that will work. The repair guys have their ways of hunting down unlocked phones and can probably see yours has been unlocked too.
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