I knew that it used to stand for that (and as an acronym should be upper-case), but I thought they maybe dropped that somewhere along the way.

Fortran and Cobol used to be "FORTRAN" and "COBOL", too, but once systems with support for upper- and lowercase-letters became widespread, they went mixed-case.

I recall there was some debate if the name BASIC had been intended as an acronym initially, but in time, evidence (AFAIR, anyway) tended to support the claim is was an acronym from the very beginning. (-: