It sounds silly at first but I suppose there is some truth in it.
Some brands of strings do seem to need more stretching than others to settle in, and because of the importance of balanced tension between the strings and springs on a floyd rose a very 'stretchy' string would be a pain to tune up and get a decent bridge angle, much more so than a strat type trem and infinitely more annoying than any kind of non-trem guitar.
Whether Ernie Ball's are particularly stretchy I don't know as I haven't used them for quite a while.