Well, it’s good to be missed(!)
But the cute thing is that while John’s being sarcastic here, he also knows he WAS missed. Because he knows what it means when he finds his chair back in its place later on. ^_^
Well sure, he realized Sherlock missed him so he made a sarcastic comment/joke to deflect because ohnoemotion
John “Get those feelings away from me” Watson.
Now you see why he lets everybody think his middle name is Hamish.
Sometimes I think half the reason Sherlock is so “I don’t care about anybody” is to avoid freaking John out with displays of affection.