But I never had such problems before, so my question : did you change something on server-side ?
Yes, months ago. It's well tested and doesn't alter the previous behavior. Mainly just minor bug fixes and new features for TA 3.3.
Am I doing something wrong in my code ?
Perhaps, I'm not sure. I'd have to see your code.
Can I prevent this (I already sending a ping to wyday.com and executing IsGenuine() only if the request is ok) ?
Yes, with TA 3.3 will fix this problem.
Unfortunately pinging wyday.com doesn't cut it because this introduces a race condition between when you ping wyday.com and when you call IsGenuine(). Plus, if customer has an intermediate filter (wifi screen, hosts file intercept, DNS block, "web based" firewall block --- basically anything that "injects" itself into the response instead of the proper response from the LimeLM servers) then prior to TurboActivate 3.3 IsGenuine() would return TA_FAIL and deactivate the user. Plus if you're pinging wyday.com how do you know the response you're getting is actually from wyday.com and not a "filtered" response?
So don't ping wyday.com. It doesn't solve the problem (it actually introduces new problems).
My customers need proper explanations, so they don't panic : my product is used in realtime, so it's not acceptable to be deactivated in the middle of a show !
TA 3.3 is coming soon. If you want to push an update to your users right now using TA 3.2.2 then comment out your calls to IsGenuine(). Or wait another 24 hours for TA 3.3 and then include that and push that as an update.