"Not…now…Vinyl."

Oh, I get it: Octavia clearly has terminal cancer, and her insurance company dropped her coverage because of a pre-existing condition (she had a runny nose when she signed the contract). In order to pay for her life-extending treatment she had to cut back on a few necessities, including new underwear, which is why she stole Vinyl's.

Also, that cello is secretly a meth lab.

Who would have expected a concert cellist to just go and break bad like that.