PS 5.5.28 mysql server swapping even when 4-5G memory is available

Hello,

I 'm seeing couple of mysql db master swapping and using 3-4G of swap memory , but strangely db server has 4-5G free RAM available.

Any idea why mysql is using swap when server has enough ram .

Swappiness is set to 0 on these server .

[db1 ~]$ free -g
total used free shared buffers cached
Mem: 125 122 3 0 0 10
-/+ buffers/cache: 111 14
Swap: 15 4 11