Check cooked lobster meat for shell fragments and cut larger pieces into bite-sized chunks, keeping some pieces slightly bigger for texture. Place in a bowl and keep chilled.
In a small bowl, mix mayonnaise, lemon juice, salt, and pepper until smooth. Taste and adjust if needed.
Add lobster meat to the dressing and fold gently to coat. Add celery and herbs if using, and stir just to distribute.
Heat a skillet over medium heat and melt butter. Place split-top buns in the pan, pressing lightly, and toast until golden brown on both sides.
Open each toasted bun and spoon the lobster mixture inside. Fill generously but do not pack down. Optionally top with a squeeze of lemon or fresh herbs. Serve immediately.