Gurgling noise under Transmission
 

I have a 2003 4.4i 80K miles, yes there is that hissing noise from underneath and from what I read its normal at cold startup. But I drove the truck onto ramps and listened closely and under the transmission Oil Pan I guess I hear "gurgling" noise like transmission fluid is boiling, I can't figure out where its coming from, its a bubbling/gurgling noise. I have no transmission shifting issues or delays or anything like that. Anyone out there have a clue? Could it be low transmission fluid somehow just a tad bit low thus maybe air is inside and gurgling? Thanks in advance. BTW I used my Peake OBD tool and no codes.