How would you react if you see someone in public reading the same book as you?

I was on the bus the other day, and as I was reading my book, some guy showed up smiling from ear to ear showing me the same book in his hands. I for some reason was thrilled too and was like "here is a man with a taste!" and I gave him a thumps up. My problem is that it went to an awkward silence where neither party was saying anything and I thought to myself maybe I should engage in a small talk? or nah? Idk. I wanted to talk to the guy but I just couldn't bring myself too (shyness). I thought reading the same book is not enough common ground to start a small talk (I wish I didn't though).

What do you guys think? How would you react? Would you talk? Or would you smile them away?