Questions asked using past tense, some examples like: "Would you mind...?", "Could you please...?", "Should I do...?", "Did you want...?"
It seems people are using past tense in these sort of questions, when the correct tense grammatically is present tense.
Why is that?
Is this a hint of being polite or humble? Is there a grammar rule for this setup? Or is this wrong grammar but usual usage?