Water leak from underneath the bathroom sink? I just have a contractor instal new bathroom cabinet and sinks. There...

I just have a contractor instal new bathroom cabinet and sinks. There is slow drip leak underneath the sink, origniating from where on earth the 3 holes of the countertop, connect to the faucet. What should I say to the contractor? or should I hire a plumber? or is this fixed?
Answers:    Contractor desires to come back and tighten the faucet connections.
** You might want to turn sour the 2 feed lines to the faucet so your different vanity doesn't receive ruined.
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