No, it is not typical to feel a "crunchy" sensation around the navel three months after an abdominoplasty. Recurrent seromas are uncommon. This may be the result of a reaction to the suture material (stitch) which was used for your abdominal plication. I would address this with your surgeon. There are a number of techniques they can use to make this better. The symptoms which you describe are not what one would expect with a healing seroma.
Is it part of the healing process for seroma around navel post tummy tuck to feel crunchy/crackly?
Thank you for your question and I am sorry to hear of your healing difficulties. Crunchiness is not a normal sensation at three months after a tummy tuck unless you recently had a seroma drained. Crunchiness is usually described by patients who have had air develop in and around their fat cells and is typically absorbed by the body in time. If this is a recent finding I would have you see your surgeon for an in-person examination. Hope this helps.