Can I fight this ticket?

I got a new registration identification card in the mail from the state (Illinois) last month for 2012 as my car registration expired as of May 2011. Because I was absent minded, I forgot to order a new sticker until this past weekend. I got a ticket for expired plates on 6/2 and 6/16 from two different cities. I also got another ticket today (after I paid for the new sticker and it's in transit to my mailbox as we speak). Can I contest these? Seems a bit ridiculous. Ive been told by some people they won't ticket you for a month after they expire, but these cops are HOUNDING me.