I've worked at 2 companies in the last 14 years and they both got really shitty after being acquired by a private equity firm. It usually takes 2 years until it's unbearable. I stayed so long because they were wonderful jobs; work and pay; and growing like wildfire before the M&A.
Do you not look around unless you are miserable?
The only recruitment calls I ever get are from body-shop class contracting firms that never manage to even come close to my current compensation for scut work.
Another guess is that I had a recently listed promotion to Lead Developer on my LinkedIn account. Anecdotally I've heard similar experience from other people who started getting more high quality contacts once their job title on LinkedIn reflected a more senior role. I know we all hate LinkedIn but it matters because people on the hire side use it extensively, so spend some time entering details in there so that it's as impressive as your resume.
Then again, curiosity doesn't hurt either.
You don't have to be miserable just to look for another job that will pay more.