Fiat48,
In my Pop's flatbottom (Pro-Eliminator/Top Alcohol Flat - best E.T. 6.99 : best M.P.H. 149) when I would let out of the gas at the end of the 1/4 mile, I would see the same thing EVERY TIME.
Before we switched over to a dry-sump system, we were using a Dan Olson wet-sump oil pan and a System-1 billet oil pump. It would have 0 psi registering on the Oil Pressure Gauge at the end of the pass. When I looked over and saw that, I would then "burp" the throttle once or twice and the oil pressure would then come back up to "normal" (100 + psi).
After we switched to a dry-sump system, we never had that problem again!!