Recently started having a problem with my single-lever kitchen faucet. When I turn it on, sometimes the water comes out and sometimes it doesn't.

[me whistling the tune of "twilight zone"] So, we end up "pumping" the handle a few times to see if the water will come out this time , or this time , or this time?
Reading some of the other posts about water pressure, I tried the faucet all the way cold and then all the way hot to see if it was just
one of the lines. Guess what? Perfect pressure on both!

In a possibly related note, a week ago I noticed the bath water was a bit discolored, so maybe some water main issues...
So, should I call:
-ghostbusters?
-a plumber?
-the water department?
p.s. up to this point it has worked fine since we moved here 2 years ago and it is the only faucet effected in the house.
Thanks.