Oil light on dash.

Hey guys, i think im posting in the right section lol. Anyways i just put a double pumper carb on my duster (if this makes a difference) And i took it around the block and now the red oil light on the dash is coming on. I have a mechanical oil pressure gauge in my car and it read 80 when started and 40 to 60ish when driving depending on how much i was into the throttle. This is the first time ive seen this light on on the dash its right next to the brake light. What does this mean? Thanks.