No, a surprise would be throwing US agents in jail.
They can't do that to "legal" agents. "Legal" agents are US Embassy employees recognized by the host government as diplomats with immunity. "Legal" agents usually have some silly, trivial sounding titles, like, "The Under-Secretary for Cultural Exchange". But their real job is gathering intelligence, and the host country knows that and tolerates it. These folks are quite easy to spot: Just look for someone who is obviously way to intelligent and clever for his job. Like someone with a Ph.D. in international affairs from Harvard and Yale who is doing clerical work at the embassy.
Lots of intelligence work is actually quite boring, and not the James Bond stuff that you expect. The agents collect and assess political sentiment and economic developments and trends in that country. The CIA gives the President of the US a short briefing every morning for breakfast, and informs him if something is amiss somewhere in the world that needs his immediate attention. During this meeting the President also instructs them which areas he thinks need their "special attention".
This is definitely regular international diplomacy stuff.
When countries who aren't quite on the most friendliest of terms get in a huff, like Russia and the US . . . they will take turns tossing out some of each others' small fry "legals" described above.
The occasional persona non grata happens.
The CIA Station Chief is not an occasional persona. That's usually taboo among allies. Russia knows who the CIA Station Chief is in Moscow. But they do not toss him out. The US knows who the SVR Resident is in Washington, as well . . . and leave him alone.
Tossing out the CIA Station Chief is a serious diplomatic escalation, which is why it is getting so much press coverage.
Oh, here's an interesting Pro-Tip: If a foreign diplomat wants to hand you a piece of paper with an explanation of why their country just did something very nasty . . . you don't touch it. You instruct him to read it out loud. If you put your hands on it, his country will report that you "accepted" the explanation. If you don't, you will only hear in the news that the diplomat "read out load" or "recited" the explanation. This is the next thing that you will hear about this, as the professional diplomats from Germany and the US try to paper over the cracks left by the spooks.