Is a GFCI allowed to be below a washer water connection?
Well, the GFCI receptacle will protect things plugged into it.  However nothing protects the GFCI receptacle, and if water gets into the junction box behind the GFCI, it can potentially "go around" the GFCI and electrify the walls or a puddle.  

The right answer to that is to move the GFCI to a location that feeds this location. This might be another receptacle somewhere, or it might be straight to the circuit breaker itself.  Locate a GFCI there, either as a receptacle at that location, or a GFCI breaker.  Then, place the line to this washer location on the LOAD terminals of that GFCI.  Fit a plain receptacle here.  Now, if water gets into the junction box, that upstream GFCI will trip and protect the wire, receptacle, and everything plugged into it.