Como se (as if) takes the imperfect subjunctive, whatever the tense of the rest of the sentence:

• Ele fala como se fosse carioca. — He talks as if he were from Rio.
• Ela me tratou como se eu fosse da família. — She treated me as if I were family.
• Eu lembro daquele dia como se fosse ontem. — I remember that day as if it were yesterday.
• Ele dorme como se não tivesse problema nenhum. — He sleeps as if he didn't have a care in the world.

English often uses like here — He talks like he's from Rio — but Portuguese keeps como se + subjunctive.