Recently i havent had that much time playing ranked solos so my elo has been stagnant for a while. But when i loggen in today it hade dropped by 27 elo. It is not the elo drop that bothers me (maybe a little), but the fact that i dont know if it was intentionally dropped or a cause of a nasty bug.
Please investigate into this matter.

You only lose elo if you don't play ranked for over 4 weeks if you're over 1400 elo. The elo will decay to 1400 elo and not less.

http://leagueoflegends.wikia.com/wiki/Elo_rating_system

Elo decays over time when you are above 1400 Elo:[5]
Elo decays at a rate of 25 Elo for every 4 consecutive weeks of inactivity.
For normal rating, inactivity is defined as no activity in any queue.
For ranked rating, inactivity is defined as no activity in the specific queue (arranged 5x5, arranged 3x3, and solo/duo 5x5 are all tracked separately). Ranked decay also applies to people who are ranked and above 1400 rating.
The decay timer is reset after a game is played in that specific queue.
Elo will not decay below a rating of 1400.

thanks for the answer!

guess i'll have to find the some time and play ranked soon then ^^