Leakage current to heat sink
240V AC at 50 Hz and 10 uA means an impedance of 24 Mohms. But almost certainly this is due to capacitance so, at 50 Hz this is a capacitance of 133 pF and probably not anything to do with real resistive leakage.

So, estimate how much capacitance 5x T0220 bodies have when bolted down to a large large heatsink via insulators.

Is this a problem? No.