Served My Boss a Surprisingly Strong Drink Tonight

Tonight was one of those nights where I just wanted to stir up a little chaos at work. So when my boss ordered his usual vodka soda, I decided to make it extra strong. I watched him take that first sip and see the surprise on his face, it was perfect. He didn't say anything, but I saw him hesitate before finishing it off. Is this just me getting bored with my job or is it normal for someone to mix things up every now and then? What do you think?