I haven't had that particular beer, but I'd say you probably got a bad six pack. I've never tasted anything plastic-like in any of the ESBs I've tried.
Up Next: English Barleywine, Quadrupel, Ordinary Bitter
Primary: Accidental Lambic, Saison, Tripel, Petite Saison
Bottled: Brett B. Tripel, Dubbel, Robust Porter, Black IPA, Cal Common, APA, ESB, Imperial Red, Oatmeal Stout, Tafelbier, Chili Pepper Smoked Porter(s)