My white mesh nike free 5.0 NRG turns blue

[popskato]

I just bought a pair of nike free 5.0 nrg from a warehouse sale. Wore it the first time whole day at work and I noticed the white mesh turned blue-ish, need to know the cause and how can I get it off. Was wearing black socks inside.

View media item 1474711View media item 1474712