At 2 months post-op, some redness and firmness in the middle of a C-section scar can still be part of the normal healing process, since the middle tends to take longer than the ends, but because it's raised and the redness comes and goes, it would be worth bringing it up with your gynae or PD at your next visit just to rule out anything like a hypertrophic scar or early keloid forming. It's hard not to worry as a first-time mum, but having a doctor take a look in person will give you much more peace of mind than guessing, and they can also advise whether something like silicone gel or sheets might help with the scar over time.