maintenancetool --checkupdates needs admin rights on Windows

Our application uses an online installer. It is installed in

C:\Program Files (x86)\MyCompanyName\ (admin rights for write access needed).

With version 2.0.5 we check on every start of our application if there are new updates available. We execute the check hidden in a background thread. The user does not notice this:

void Updater::run() {

QStringList checkupdates("--checkupdates");
int exitCode = QProcess::execute("maintenancetool", checkupdates);

...

}

Now, in version 3.0.1 a Windows message pops up asking for admin rights. Is this a bug or is there a new way for a silent update check?