what is the difference? "if i saw you in heaven" and "if i see you in heaven"

Posted by modo on 2014/1/24 12:11:22
http://www.youtube.com/watch?v=sSbqm7ZK_9s

the lyrics of song "tear in heaven"

would you hold my name, if i saw you in heaven.

why using "saw"?

Thanks

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