Replaced Valve Spring

I just got my car fixed and its running good, haven’t pushed it yet. The problem was that a spring valve broke. Now the mechanic only replaced one, the one that broke. Should he have replaced all of the spring valves? Since the new one has 0 miles on it but the other ones have about 27k miles on it. Would this cause a problem later on or is it okay just to replace one.

I would think that you should be fine for quite a while because these do not normally go bad so you just happened to get one with a flaw.