[Chad C. Mulligan]

Best bet - you have air trapped somewhere in the unfrozen part of your piping. This is compressed, and absent pressure from the pump tank will drive water flow from your spigots for a short time. Hot water tank is a good candidate.

[Paul R.]

Well, I considered that (pipe was already frozen), but, I'd flushed the toilet & just at the end of the refill and me doing a quick hand wash the well pump came on (easily audible from bathroom). So, the pump would have replenished the tank to 45 psi. Then (under 10 min. later) I drew it down from 45 psi it "must" have been at to the 38 psi I observed. At that point (running shower, brushing teeth) then the water abruptly went from that 2 -2.5 GPM, to nothing quickly -- I'd say about 3 seconds.