For (ethnic) Romanians non-Romanians are all "foreigners", minorities, immigrants and all. I don't think there are that many recent immigrants in Romania, and most of them would be Westerners, who would generate the exact opposite of resentment. Minorities are a different issue altogether: according to the propaganda of the seventies and eighties they are vagrants who abused Romanians' hospitality. This was read as an anti-Hungarian barb: as opposed to Romanians, who'd lived there from time immemorial, Hungarians were these loose migrating tribes that made Romania their home. (It doesn't matter that this took place more than 1000 years ago, and it is debatable whether that territory would have qualified as Romania back then.) At any rate, this was the propaganda I grew up with: as Comrade C. pandered more and more to nationalism, one of the main "arguments" against Hungarians was that they are an inferior, vagrant bunch. As with all official propaganda, some bought it, some didn't. Some Romanians, who were not so fond of Hungarians in private, nevertheless resisted gov-t induced chauvinism, because they resented the government for other reasons. (Not to mention decent Romanians, for whom all this was a constant shame.)

I would not be surprised that many Romanians still have mistaken notions about minorities: under the old regime there was NO unbiased official information, there was no official effort to raise the awareness of ethnic Romanians (from homogeneous areas), to make them acquainted with the culture and history of these groups. On the contrary, all an average Romanian would hear about minorities would be that they are abusive guests, parasites, you name it. Things have been VERY SLOWLY improving since 1989, but it will take a long time until Romanians come to fully accept the fact that R. is a multicultural, multilingual society. In this process, the differences between R's regions are bound to become deeper. On my sporadic visits Transylvania does seem to be proudly multicultural, with many Romanians voluntarily learning the once-derided Hungarian language, but I am a bit sceptic (and uninformed) about the other regions.

P.s. For the record, I'm an ethnic Hungarian who grew up in Transylvania. Some stuff I wrote about Ceausescu's propaganda may sound harsh and biased, but unfortunately  those texts and manifests WERE pretty awful. One good thing was that many people were just deaf to all this, out of a healthy E-European distrust for officialdom.

A dog's a dog. A Cat's a Cat. (T.S. Eliot)