Maybe your browser is set to tell web sites that Spanish is your preferred language. If that were the case, though, you'd be getting more Spanish content pushed at you by more web sites. Still, you might want to check your browser settings; can't tell you where, it varies by browser, from prominent on a menu to buried deep in a dialog box.

The other possibility is likely zip code profiling--your IP address resolves into a zip code at which demographic data says a lot of people sprechen zie espanol.

Maybe it was your refusal to act on the initial English buy! command that forced them to resort to a possible second language. You may need to buy the fabric softener, and be sure to use a coupon, store loyalty card, or pay with credit card, in order to get your purchase put on your permanent record. Then they'll just bombard you only in English to keep you going back for more. That'll make it better, right?