Oncidium twinkle leaves browning at the tips

[sweta]

Hi all,

I recently purchased this oncidium twinkle that is close to maturity. It came potted in bark and sphagnum moss. I repotted it in sphagnum moss and bark just to get rid of any possible pests that might have come from the growers greenhouse. Plants seems to be doing fine except for some of the leaf tips turning brown. Also I've notice whitish streaks on some leaves. Is it anything to worry about? Please help. House temperature is at 70F and i use tap water for watering. Pictures are attached.