Item #281633139128
Final price: 423.00
Snipe: 480.88
Status from eBay:
Bidding has ended

I placed the bid with 3 seconds to go, any reason why this failed?

I see there was a short period of some network lags around that time, so the sniper did not have enough time to resubmit your snipe.
This is rare, but may happen sometimes.

Please keep the default 5-6 seconds snipe unless you accept the risk for your snipe to miss due to possible network lags and things like that.