[Jprogramming] (1 _10)H.(_10)2 evaluates to infinity

['Bo Jacoby' via Programming]

I was given this hint on how to compute a hypergeometric sum
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    F =. 3 : '+/(2^i)*|:(!/~)|.i=.i.>:y'
     S =. 4 : '(y!x)*(1,-y)H.(-x)2'
     G =. 3 : '>y(S&.>)i.>:y'
     F 10 
1 12 67 232 562 1024 1486 1816 1981 2036 2047
    G 10

1 12 67 232 562 1024 1486 1816 1981 2036 _
     wa=. 4 : '((x=y)*<:2^>:x)+(-.x=y)*x S y' NB. work around
     H =. 3 : '>y(wa&.>)i.>:y'
     H 10
1 12 67 232 562 1024 1486 1816 1981 2036 2047
Question: Is it a bug that  (1 _10)H.(_10)2  evaluates to infinity?
Thanks! Bo.