Did a water on concrete evap / absorb test a while back and it's pretty damn fast, like under 30 seconds in a low humid environment. This, apparently was standing long enough for mosquitoes to lay eggs in, possibly hatch. When I tossed a towel on it to dry it like 8 mosquitoes popped off it. Sprayed soap, bug killer, fire and aids onto the spot to kill all of the eggs and mosquitoes. I stand by my OG statement though, I didn't notice it yesterday afternoon (10-2 pm) before the rain and I did walk on that side of the garage.
Done and will check it later. What makes me wonder is it appeared right under that discoloration of the concrete making me think there may be a copper line under that point MAYBE for AC / water heater drainage, I really hope not...but there may be.