RBTA vs Mille

[doch]

OK... here's the scoup: I left town for the weekend, came back and surprise surprise, my RBTA has moved to the dead centre of my tank. Unfortunately, it's touching a really nice blue (oddly enough it was red in my other tank) mille, and another acro that I could care less about. Naturally, the acro that I could care less about is VERY easy to move... the mille that I love is not. So far I see no damage to either one of them... should I just leave well enough alone, or should I be concerned? If I should be concerend, which one will get the beating?