It's difficult/impossible tell when you got it.

The number itself doesn't mean much other than it's a positive. Your reading of 1.53 is in the low positive region so it is usually recommended with that with low a reading that you retest after a few weeks as confirmation. If the questionable encounter was a week and a half ago, it's unlikely that this result is a new infection from that incident. It's pretty early for that to be producing detectable antibodies.

If you already have the virus, then the two of you aren't passing it back and forth.

You might ask your question over at
http://racoon.com/cgi-bin/dcforum/dcboard.cgi
in the support forum. You should get some pretty good answers there from some gals who know their stuff.