While I do generally commend people for playing their job well there are certain exceptions.
I might give the comm to new players, cause it's hard to get a lot of comms these days, when most people just sprint through duties and run out without giving comms.
If I had a nice talk to someone during the run, I give them my comm.
Depending on my mood, I might throw comms out for funny ways to die, making them feel better about a mistake they made, encouraging them, or because I like their glamour.

Long story short, there's a bunch of reasons people give commendations and you shouldn't interpret too much into it. Be happy you got one