Is soft, squishy swelling normal after gynecomastia surgery? Or is it a seroma?

Dear aulay,it is hard to tell without an examination. I would suggest you to consult your plastic surgeon. Only after a thorough examination you will get more information and recommendations.Daniel Barrett, MD, MHA, MS 
Certified, American Board of Plastic Surgery  
Member, Am. Society of Plastic Surgery

Thank you for submitting your question. It sounds like you're wearing your compression garment as instructed. If you have an asymmetric swelling that feels fluid like, I would recommend evaluation by your surgeon as early as is convenient. A phone call to let them know what is happening is important. Many times this is nothing and will resolve. I would air on the side of caution and make your surgeon aware.
Good luck!
Dr. K

You are still in the very early days following surgery and a degree of swelling is still to be expected.  It is often different on side compared to the other and from your description a small amount of serum fluid may be present.  It would be best to have this evaluated by your surgeon.  Small seromas are often left as they are likely to dissipate on their own,

best wishes