Please Help!

Hey everyone! So I've had the mirena for about 2 and half years now, and I've not had a period since about two days after getting it placed. Well my boyfriend and I are long distance and so we had quite a bit of sex when I saw him. The next day I had a bit of light brown spotting with no cramps and I could feel the stings on the mirena and they felt fine. This lasted a day and a half and was never anything more than wipe away blood. Is this something I should be worried about ? I made the mistake of googling it and saw something about implantation bleeding...but the timing isn't right and I feel perfectly normal during the bleeding and still after.