Some schedulers in SS will first ask if you're willing to be released from duty for your 10 hours in order to cover a standup/redeye, but they seem few and far between. Most of the time however, they'll just tell you they're releasing you from duty without implying that the choice is actually yours on whether you choose to accept it or not. To someone on reserve who doesn't know better, it sounds like it's mandatory and you of course accept, which is what they want.