Hex Chest Monthly limit bug

Ok so I think I have found a bug that affects you getting chest. I received a S on Udyr when I had already got all 4 chest I was allowed that month (so I didnt get a chest), when I had another chest available to get I used Udyr again and got another S in my premade party and still didnt receive a chest. So the bug I think I found is, if you get a S on a champion and have not chest available to get due to monthly limit if you go back and get a S on that champion again the system is counting as it has already given you a chest. Anyone else experience this issue? I would post a screen shot but it doesnt really show anything other than i recieved a S.