4 weeks post TT and can feel a wave/bubbles on the side of me when I press down. Is this a seroma?

It is not uncommon for a patient to develop a seroma after tummy tuck surgery, even if drains were previously used. The symptoms are exactly as you describe - a sloshing, undulating water wave (like a waterbed). It's nothing to worry about; if clinically significant, your surgeon will drain it with a small needle under local anesthesia (perhaps needing to repeat that a few times over a couple of weeks) and it most likely will subside. Rarely, a new drain might need to be placed if the seroma does not resolve with serial drainages. Once the fluid volume is down to about 20cc of potential space, your body is likely to absorb the fluid and seal the space. If it is very uncomfortable, you may want to go in before your scheduled appointment, but otherwise it can usually wait a few days.

Thank you for your question. Based on the description you may have seroma. I recommend you to see your PS for evaluation.