Not surprised. Fans were always clamoring to get him back but once you trade a player in this manner it doesn't seem like they ever come back.
For one, the team is generally down on the player compared to the market (hence the trade). Second, the player is understandably going to harbor some feelings for getting dealt.
The major exception is when soon to be FAs are traded at the deadline. The situation is more understandable for both sides. Rickey Henderson re-signed with the A's after he got traded here, Yimi just signed with us, etc.