[UK-CONTEST] AFS contest etiquette

[Ray - G4FON]

I started late yesterday but found a clear frequency and had a reasonable run going when I was called by G3MIR, who I worked. The
next station to call me immediately afterwards was G4FBS. 

Once I finished the QSO with G4FBS, I was stunned to hear G3MIR call him on my frequency and send him a report.

Is all fair in love, war and contesting these days or is this operating practice out of line?

73

Ray, G4FON