Traveling - My Call or Not?

[Wondering]

NFHS home Team A, is down by two points and inbounds at the far end of the court with 3.2 seconds left in the game. I'm the lead, watching team watching most of B's players defending under A's basket.

Team A inbounds the ball, and passes to about A1 about half way between the division line and their 3-point circle with about 1 second to go.

My partner is a 1st-year ref and I'm trying to spread my coverage to see the entire half court. I clearly see A1 travel before launching a very long 3-pointer. This travel is clearly in his area, since I'm under the basket.

I assume he'll call a travel - he's only 10 feet away from A1 and has a clear view - but by the time I realize he isn't going to whistle, the 3-pointer is in the basket and the final horn sounds.

The home crowd immediately rushes onto the court, the visiting couch yells "wasn't that a travel?" as I ask my partner "didn't you see a travel" and he replies "No - I'm pretty sure it wasn't".

So I let it go.

Did I wimp out?????