Copper Iud

I just got a copper iud inserted on day 2 of my cycle. My normal cycle before the IUD would be heavy on the first 2 days then medium till the 4th or 5th day with spotting on day 6. Well, my cycle after getting the IUD got lighter. I was heavy the morning I got it, but almost immediately my cycle turned light and only lasted a total of 4 days. I’m not complaining but find it very odd. I was expecting my period to be a little heavier. Any thoughts?!?!