A refrigerant leak could still drip oil from the system, but if it dries up and goes away then it could only be A/C condensation, windshield washer fluid, or coolant to a lesser extent. Everything else stays an oily wet mess. The question is does stopped after 6 hr mean it just stopped dripping and still a wet looking patch below it, or that it was all dried up at that point?
You may be able to see dark brown/black oil or dark red ATF on pavement, but otherwise it's hard to see if fluid is really clear without putting down some newspaper to see what color it shows up as on white, or catching a drip before it hits the ground.