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: Lamebic, Flanders Red, Malt Liquor, Belgian IPA
Primary: English IPA, Spiced Winter Warmer, Brett. C. Old Ale
Secondary: Sour Stout, Brett C. Wild Bitter
Polypinned: Best Bitter
Bottled: Sticke Altbier, Doppelsticke Altbier, Weizenbock, Berliner Weisse, Spruce Brown Ale, Arrogant Bastard Clone, English Summer Ale, Coniston Bluebird Bitter Clone v1.5
In the "cellar": Brett B. Tripel, Quadrupel, Tripel, Brett C. Oaked English Barleywine, Lamebic