Fluid retention within the tissue...sloshing or gurgling sound when rubbed or stroked

A sloshing or gurgling sound is very common in the first few days after breast surgery.  It will not harm you, and it is almost always quite temporary.  During surgery, small pockets of air are created in the breast pocket.  Normal post-operative swelling creates some fluid, and these subsequent air-fluid pockets create bubbling or gurgling sounds.  The air will eventually be absorbed naturally by the body during healing, and the gurgling will stop.  But be sure to discuss this phenomenon with your surgeon during your post-op visits.  Good luck.

Congratulations on having undergone the breast reduction procedure. Much of what you describe is commonly experienced after breast reduction surgery;  in other words, there is nothing in your description that sounds concerning. However, nothing will replace direct communication with your plastic surgeon who will be your best resource when it comes to an accurate assessment, advice, and/or meaningful reassurance.   Best wishes for an outcome that you will be very pleased with.