yes a dented oil pan will cause it, what your problem is is that when your oil is cold it is thicker and your oil pressure is rising above 50 psi. when it heats up the viscosity changes as does your oil pressure, and with a dented oil pan the pickup may not be getting enough flow from the sump or it could be bent, i have personally seen that happen twice on honda's.

this is dumb, but also check your oil level.

as said before your vtec should not be working when the engine is cold, the gauge should be about 1/4-1/3 up off of the cold mark to allow vtec to operate, unless you have a vtec controller or other hackjob.

if you do not have an oil pressure gauge, i highly recommend getting a cheapo sunpro that you can connect temporarily in the engine bay just to make sure that your pressure is up to par, dummy light wont come on until pressure is stupid low, iirc less 5psi or so

check all your sensors and wiring, make sure there are no broken wires or shorts etc..., if you find no problem there i guarantee that your problem will be revealed with oil pan removed, trust me i almost tore a b20vtec completely apart because of low oil pressure and it turned out the pickup was a little bent