Could we have done this different?

[HugoTafurst]

2 Umpire FP Mechanics
R1 (at 1st) -

Bunt 3/4 of the way to the pitcher's circle about 1/2 way between 1B foul line and line to pitcher's plate.

Ball is fielded and thron to F4 covering 1st.
BU calls the out.
PU having moved up first base line to observe the play then advances toward third as F4 throws across.
R1 is about 1/2 way between 2nd and 3rd as F6 gets the ball and tags R1 as she stops and then tries to retreat to 2nd.
BU calls the out...
3B Coach asks PU why he didn't call Obstruction at 2nd base.
Neither PU nor BU saw the possible obstruction at 2nd as they both were concentrating on the action at 1st.

PU broke off to cover R1 possibly advbancing to 3rd, but it was after any infraction would have occurred at 2nd.

Did we blow the mechanic or is this one of those $65.00 calls?

I was PU and having this happen, I tried to widen my field of view as I was watching the play at 1st, but in the end, I've got to see that pull/no pull.
My BU, of course has to get the out/safe.